Chemical compounds

ABSTRACT

The present invention relates to azaquinolone compounds of Formula (I), and their use in medicine.

The present disclosure relates to substituted azaquinolone compounds andpharmaceutically acceptable salts thereof that inhibit the Poly(ADP-ribose) polymerase (PARP) family of enzymes. The present disclosurealso relates to the use of these compounds, and pharmaceuticallyacceptable salts thereof, in medicine, for example in the treatment ofdiseases in which inhibition of PARP1 or PARP1 function is oftherapeutic significance. The present disclosure also relates to methodsof treatment and methods of manufacture of medicaments using compoundsaccording to the disclosure.

PARP family of enzymes play an important role in a number of cellularprocesses, such as replication, recombination, chromatin remodeling, andDNA damage repair (O'Connor M J, Mol Cell (2015) 60(4):547-60).

Examples of PARP inhibitors and their mechanism of action are taught ine.g. WO2004/080976.

PARP1 and PARP2 are the most extensively studied PARPs for their role inDNA damage repair. PARP1 is activated by DNA damage breaks and functionsto catalyse the addition of poly (ADP-ribose) (PAR) chains to targetproteins. This post-translational modification, known as PARylation,mediates the recruitment of additional DNA repair factors to DNAlesions.

Following completion of this recruitment role, PARP auto-PARylationtriggers the release of bound PARP from DNA to allow access to other DNArepair proteins to complete repair. Thus, the binding of PARP to damagedsites, its catalytic activity, and its eventual release from DNA are allimportant steps for a cancer cell to respond to DNA damage caused bychemotherapeutic agents and radiation therapy (Bai P. Biology ofpoly(ADP-ribose) polymerases: the factotums of cell maintenance. MolCell 2015; 58:947-58).

Inhibition of PARP family enzymes has been exploited as a strategy toselectively kill cancer cells by inactivating complementary DNA repairpathways. A number of pre-clinical and clinical studies havedemonstrated that tumour cells bearing deleterious alterations of BRCA1or BRCA2, key tumour suppressor proteins involved in double-strand DNAbreak (DSB) repair by homologous recombination (HR), are selectivelysensitive to small molecule inhibitors of the PARP family of DNA repairenzymes. Such tumours have deficient homologous recombination repair(HRR) pathways and are dependent on PARP enzymes function for survival.Although PARP inhibitor therapy has predominantly targeted BRCA-mutatedcancers, PARP inhibitors have been tested clinically in non-BRCA-mutanttumors, those which exhibit homologous recombination deficiency (HRD)(Turner N, Tuft A, Ashworth A. Hallmarks of ‘BRCAness’ in sporadiccancers. Nat Rev Cancer 2004; 4: 814-9).

It is believed that PARP inhibitors having improved selectivity forPARP1 may result in improved efficacy and reduced toxicity compared toother clinical PARP1/2 inhibitors. It is believed also that selectivestrong inhibition of PARP1 would lead to trapping of PARP1 on DNA,resulting in DNA double-strand breaks (DSBs) through collapse ofreplication forks in S-phase. It is believed also that PARP1-DNAtrapping is an effective mechanism for selectively killing tumour cellshaving HRD.

An unmet medical need therefore exists for effective and safe PARPinhibitors. Especially PARP inhibitors having selectivity for PARP1.

The applicant has discovered that the azaquinolones described hereinsurprisingly have PARP inhibitory activity, and therefore may be usefulfor the treatment of diseases and conditions in which PARP function haspharmacological significance. Furthermore, azaquinolones describedherein have surprisingly high selectivity for PARP1 over other PARPfamily members such as PARP2, PARP3, PARP5a, and PARP6.

The applicant has further discovered that the azaquinolones describedherein surprisingly are capable of penetrating the blood brain barrier(BBB). Therefore, the azaquinolones described herein may be useful forthe treatment of diseases and conditions occurring in tissues in thecentral nervous system, such as the brain and spinal cord.

In an aspect, the applicant makes available a class of compounds ofFormula (I):

wherein:R¹ is independently selected from H, C₁₋₄ alkyl, C₃₋₆ cycloalkyl, C₁₋₄fluoroalkyl, and C₁₋₄ alkyloxy;R² is independently selected from H, halo, C₁₋₄ alkyl, and C₁₋₄fluoroalkyl; andR³ is H or C₁₋₄ alkyl;R⁴ is halo or C₁₋₄ alkyl,or a pharmaceutically acceptable salt thereof.

In another aspect, the applicant makes available a class of compounds ofFormula (I):

wherein:R¹ is independently selected from H, C₁₋₄ alkyl, C₁₋₄ fluoroalkyl, andC₁₋₄ alkyloxy;R² is independently selected from H, halo, C₁₋₄ alkyl, and C₁₋₄fluoroalkyl; andR³ is H or C₁₋₄ alkyl;R⁴ is halo or C₁₋₄ alkyl,or a pharmaceutically acceptable salt thereof.

In an aspect, R¹ is selected from any one of methyl, ethyl, isopropyl,cyclopropyl, 1,1-difluoroethyl, 1-fluoroethyl, trifluoromethyl,difluoromethyl, and methoxy. In an particular aspect, R¹ is methyl orethyl.

In an aspect, R² is selected from any one of H, chloro, fluoro, methyl,and difluoromethyl. In an aspect, R² is fluoro or methyl.

In an aspect, R³ is methyl or ethyl.

In an aspect, R⁴ is selected from any one of chloro, fluoro and methyl.In a particular aspect, R⁴ is fluoro.

In an aspect, there is provided a compound of formula I, wherein R¹ isC₁₋₄ alkyl, R² is halo, R³ is C₁₋₄ alkyl, R⁴ is halo or C₁₋₄ alkyl, or apharmaceutically acceptable salt thereof.

In a further aspect, there is provided a pharmaceutical compositioncomprising a therapeutically effective amount of a compound of FormulaI, or a pharmaceutically acceptable salt thereof, and at least onepharmaceutically acceptable diluent, excipient or inert carrier.

In a further aspect, there is provided a compound of Formula I or apharmaceutically acceptable salt thereof, for use in treatment orprophylaxis of diseases and conditions in which inhibition of PARP1 isbeneficial. In an aspect, the specification provides a compound ofFormula I or a pharmaceutically acceptable salt thereof for use in thetreatment of cancer. In an aspect, the cancer is breast, ovary,pancreas, prostate, hematological, gastrointestinal such as gastric andcolorectal, or lung cancer such as small cell or non-small cell lungcancer. In an aspect, the cancer is breast, ovary, pancreas or prostatecancer. In an aspect, the cancer is of the brain, such as glioma orglioblastoma. In an aspect, the cancer of the brain is a metastaticcancer arising from a tumour elsewhere in the body such as breast,ovary, pancreas, prostate, hematological, gastrointestinal such asgastric and colorectal, or lung cancer such as small cell or non-smallcell lung cancer.

In a further aspect, there is provided a method of treating diseases orconditions in which inhibition PARP1 is beneficial, comprisingadministering to a patient in need thereof an effective amount of acompound of Formula I or a pharmaceutically acceptable salt thereof. Inan aspect, said disease or condition is cancer. In an aspect, the canceris breast, ovary, pancreas, prostate, hematological, gastrointestinalsuch as gastric and colorectal, or lung cancer such as small cell ornon-small cell lung cancer. In an aspect, the cancer is breast, ovary,pancreas or prostate cancer. In an aspect, the cancer is of the brain,such as glioma or glioblastoma. In an aspect, the cancer of the brain isa metastatic cancer arising from a tumour elsewhere in the body such asbreast, ovary, pancreas, prostate, hematological, gastrointestinal suchas gastric and colorectal, or lung cancer such as small cell ornon-small cell lung cancer.

In a further aspect, there is provided the compound of Formula I or apharmaceutically acceptable salt thereof, for use in the preparation ofa medicament for the treatment of diseases or conditions in whichinhibition of PARP1 is beneficial. In an aspect, the cancer is breast,ovary, pancreas, prostate, hematological, gastrointestinal such asgastric and colorectal, or lung cancer such as small cell or non-smallcell lung cancer. In an aspect, the cancer is breast, ovary, pancreas orprostate cancer. In an aspect, the cancer is of the brain, such asglioma or glioblastoma. In an aspect, the cancer of the brain is ametastatic cancer arising from a tumour elsewhere in the body such asbreast, ovary, pancreas, prostate, hematological, gastrointestinal suchas gastric and colorectal, or lung cancer such as small cell ornon-small cell lung cancer.

In a further aspect, there is provided the use of a compound of FormulaI or a pharmaceutically acceptable salt thereof, in the manufacture of amedicament for use in the treatment of diseases or conditions in whichinhibition of PARP1 is beneficial. In an aspect, the cancer is breast,ovary, pancreas, prostate, hematological, gastrointestinal such asgastric and colorectal, or lung cancer such as small cell or non-smallcell lung cancer. In an aspect, the cancer is breast, ovary, pancreas orprostate cancer. In an aspect, the cancer is of the brain, such asglioma or glioblastoma. In an aspect, the cancer of the brain is ametastatic cancer arising from a tumour elsewhere in the body such asbreast, ovary, pancreas, prostate, hematological, gastrointestinal suchas gastric and colorectal, or lung cancer such as small cell ornon-small cell lung cancer.

In a further aspect, there is provided a compound of Formula I capableof penetrating the blood brain barrier (BBB). In an aspect, the ratio ofcompound that penetrates the BBB is >0.1, wherein 1 is complete BBBpenetration, and 0 is no penetration. In an aspect, the ratio ofcompound that penetrates the BBB is >0.2.

In an aspect, the ratio of compound that penetrates the BBB is >0.3. Inan aspect the ratio of compound that penetrates the BBB is measuredusing the rat kpuu assay. In an aspect, the compound of Formula I has aratio of >0.3 (i.e. from 0.3 to 1) as determined in the rat kpuu assay.

In a further aspect, there is provided a compound of Formula I, or apharmaceutically acceptable salt thereof, for use in medicine.

In a further aspect, the compound of Formula I in the free base form.

In a further aspect, there is provided a compound of Formula I or apharmaceutically acceptable salt thereof, for use as medicament.

In a further aspect, there is provided the Examples disclosed herein.

In an aspect, there is provided a compound of Formula I which is5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamideor a pharmaceutically acceptable salt thereof.

In an aspect, there is provided a compound of Formula I which is6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideor a pharmaceutically acceptable salt thereof.

In an aspect, there is provided a compound of Formula I which is6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamidecrystalline form B or a pharmaceutically acceptable salt thereof.

In an aspect, there is provided a compound of Formula I which is6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamidecrystalline form D or a pharmaceutically acceptable salt thereof.

In an aspect, there is provided a compound of Formula I which is6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamidemesylate, optionally as crystalline form C.

Further aspects will be apparent to one skilled in the art from readingthis specification.

It is well known that blockade of the cardiac ion channel coded by humanether-à-gogo-related gene (hERG) is a risk factor in drug discovery anddevelopment. Blockage of hERG can cause safety problems such as cardiacarrhythmia. Advantageously, the compounds of Formula I have low hERGactivity. In an aspect, there is provided a compound of Formula I havingan IC50 >10 μM. In an aspect, there is provided a compound of Formula Ihaving an IC50 >20 μM.

To minimize the risks of off-target effects, it is desirable for drugmolecules to possess selectivity for a specific target. The compounds ofFormula I advantageously possess selectivity for PARP1 over othermembers of the PARP family including PARP2, PARP3, PARP5a, and PARP6.Advantageously, the compounds of Formula I possess selectivity for PARP1over PARP2. In an aspect, there is provided a compound of Formula Ihaving 10-fold selectivity for PARP1 over PARP2. In an aspect, there isprovided a compound of Formula I having 100-fold selectivity for PARP1over PARP2.

Another further aspect provides for the use of a compound of Formula Iin the preparation of a medicament for use as an adjunct in cancertherapy or for potentiating tumour cells for treatment with ionizingradiation or chemotherapeutic agents, or antibody-based therapies suchas immunooncology or antibody-drug conjugates.

Other further aspects provide for the treatment of disease amelioratedby the inhibition of PARP1, comprising administering to a subject inneed of treatment a therapeutically effective amount of a compound ofFormula I, preferably in the form of a pharmaceutical composition andthe treatment of cancer, comprising administering to a subject in needof treatment a therapeutically-effective amount of a compound of FormulaI in combination, preferably in the form of a pharmaceuticalcomposition, simultaneously or sequentially with ionizing radiation orchemotherapeutic agents.

In further aspects, a compound of Formula I may be used in thepreparation of a medicament for the treatment of cancer which isdeficient in Homologous Recombination (HR) dependent DNA DSB repairactivity, or in the treatment of a patient of a cancer which isdeficient in HR dependent DNA DSB repair activity, comprisingadministering to said patient a therapeutically-effective amount of thecompound.

The HR dependent DNA DSB repair pathway repairs double-strand breaks(DSBs) in DNA via homologous mechanisms to reform a continuous DNA helix(K. K. Khanna and S. P. Jackson, Nat. Genet. 27(3): 247-254 (2001)). Thecomponents of the HR dependent DNA DSB repair pathway include, but arenot limited to, ATM (NM_000051), RAD51 (NM_002875), RAD51L1 (NM_002877),RAD51C (NM_002876), RAD51L3 (NM_002878), DMC1 (NM_007068), XRCC2(NM_005431), XRCC3 (NM_005432), RAD52 (NM_002879), RAD54L (NM_003579),RAD54B (NM_012415), BRCA1 (NM_007295), BRCA2 (NM_000059), RAD50(NM_005732), MRE11A (NM_005590) and NBS1 (NM_002485). Other proteinsinvolved in the HR dependent DNA DSB repair pathway include regulatoryfactors such as EMSY (Hughes-Davies, et al., Cell 115, pp 523-535). HRcomponents are also described in Wood, et al., Science, 291, 1284-1289(2001).

A cancer which is deficient in HR dependent DNA DSB repair may compriseor consist of one or more cancer cells which have a reduced or abrogatedability to repair DNA DSBs through that pathway, relative to normalcells i.e. the activity of the HR dependent DNA DSB repair pathway maybe reduced or abolished in the one or more cancer cells.

The activity of one or more components of the HR dependent DNA DSBrepair pathway may be abolished in the one or more cancer cells of anindividual having a cancer which is deficient in HR dependent DNA DSBrepair. Components of the HR dependent DNA DSB repair pathway are wellcharacterised in the art (see for example, Wood, et al., Science, 291,1284-1289 (2001)) and include the components listed above.

In an aspect, the cancer cells may have a BRCA1 and/or a BRCA2 deficientphenotype i.e. BRCA1 and/or BRCA2 activity is reduced or abolished inthe cancer cells. Cancer cells with this phenotype may be deficient inBRCA1 and/or BRCA2, i.e. expression and/or activity of BRCA1 and/orBRCA2 may be reduced or abolished in the cancer cells, for example bymeans of mutation or polymorphism in the encoding nucleic acid, or bymeans of amplification, mutation or polymorphism in a gene encoding aregulatory factor, for example the EMSY gene which encodes a BRCA2regulatory factor (Hughes-Davies, et al., Cell, 115, 523-535).

BRCA1 and BRCA2 are known tumour suppressors whose wild-type alleles arefrequently lost in tumours of heterozygous carriers (Jasin M., Oncogene,21(58), 8981-93 (2002); Tutt, et al., Trends Mol Med., 8 (12), 571-6,(2002)). The association of BRCA1 and/or BRCA2 mutations with breastcancer is well-characterised in the art (Radice, P. J., Exp Clin CancerRes., 21 (3 Suppl), 9-12 (2002)). Amplification of the EMSY gene, whichencodes a BRCA2 binding factor, is also known to be associated withbreast and ovarian cancer. Carriers of mutations in BRCA1 and/or BRCA2are also at elevated risk of certain cancers, including breast, ovary,pancreas, prostate, hematological, gastrointestinal and lung cancer.

In an aspect, the individual is heterozygous for one or more variations,such as mutations and polymorphisms, in BRCA1 and/or BRCA2 or aregulator thereof. The detection of variation in BRCA1 and BRCA2 iswell-known in the art and is described, for example in EP 699 754, EP705 903, Neuhausen, S. L. and Ostrander, E. A., Genet. Test, 1, 75-83(1992); Chappnis, P. O. and Foulkes, W. O., Cancer Treat Res, 107, 29-59(2002); Janatova M., et al., Neoplasma, 50(4), 2-[6-505 (2003);Jancarkova, N., Ceska Gynekol., 68{1), 11-6 (2003)). Determination ofamplification of the BRCA2 binding factor EMSY is described inHughes-Davies, et al., Cell, 115, 523-535).

Mutations and polymorphisms associated with cancer may be detected atthe nucleic acid level by detecting the presence of a variant nucleicacid sequence or at the protein level by detecting the presence of avariant (i.e. a mutant or allelic variant) polypeptide.

Definitions

Alkyl groups and moieties are straight or branched chain, e.g. C₁₋₈alkyl, C₁₋₆ alkyl, C₁₋₄ alkyl or C₅₋₆ alkyl. Examples of alkyl groupsare methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, n-pentyl,n-hexyl, n-heptyl and n-octyl, such as methyl or n-hexyl.

Cycloalkyl groups are saturated cyclic alkyl groups. C₃₋₆ cycloalkyl isa saturated cyclic alkyl group having from 3 to 6 carbon atoms. Examplesof C₃₋₆ cycloalkyl include cyclopropyl, cyclobutyl, cyclopentyl, andcyclohexyl. C₃₋₆ cycloalkyl includes C₃₋₅ cycloalkyl and C₃₋₄cycloalkyl.

Fluoroalkyl groups are alkyl groups in which one or more H atoms isreplaced with one or more fluoro atoms, e.g. C₁₋₈ fluoroalkyl, C₁₋₆fluoroalkyl, C₁₋₄ fluoroalkyl or C₅₋₆ fluoroalkyl. Examples includefluoromethyl (CH₂F—), difluoromethyl (CHF₂—), trifluoromethyl (CF₃—),2,2,2-trifluoroethyl (CF₃CH₂—), 1,1-difluoroethyl (CH₃CHF₂—),2,2-difluoroethyl (CHF₂CH₂—), 1-fluoroethyl (CH₃CHF—), and 2-fluoroethyl(CH₂FCH₂—).

Halo means fluoro, chloro, bromo, and iodo. In an aspect, halo is fluoroor chloro.

Alkyloxy groups are alkyl groups which are connected to the rest of themolecule via an oxygen atom.

Examples of suitable C₁₋₄ alkyloxy groups include methoxy, ethoxy,n-propoxy, i-propoxy, n-butoxy, sec-butoxy and t-butoxy.

In this specification, unless otherwise stated, the term“pharmaceutically acceptable” as used herein refers to those compounds,materials, compositions, and/or dosage forms which are, within the scopeof sound medical judgment, suitable for use in contact with the tissuesof human beings and animals without excessive toxicity, irritation,allergic response, or other problem or complication, commensurate with areasonable benefit/risk ratio.

In this specification, unless otherwise stated, the phrase “effectiveamount” means an amount of a compound or composition which is sufficientenough to significantly and positively modify the symptoms and/orconditions to be treated (e.g., provide a positive clinical response).The effective amount of an active ingredient for use in a pharmaceuticalcomposition will vary with the particular condition being treated, theseverity of the condition, the duration of the treatment, the nature ofconcurrent therapy, the particular active ingredient(s) being employed,the particular pharmaceutically-acceptable excipient(s)/carrier(s)utilized, and like factors within the knowledge and expertise of theattending physician.

The term “treating”, as used herein, unless otherwise indicated, meansreversing, alleviating, inhibiting the progress of, delaying theprogression of, delaying the onset of, or preventing the disorder orcondition to which such term applies, or one or more symptoms of suchdisorder or condition. The term “treatment”, as used herein, unlessotherwise indicated, refers to the act of treating as “treating” isdefined immediately above. The term “treating” also includes adjuvantand neo-adjuvant treatment of a subject. For the avoidance of doubt,reference herein to “treatment” includes reference to curative,palliative and prophylactic treatment, and to the administration of amedicament for use in such treatment.

The compounds of Formula I may form stable pharmaceutically acceptableacid or base salts, and in such cases administration of a compound as asalt may be appropriate. Examples of acid addition salts includeacetate, adipate, ascorbate, benzoate, benzenesulfonate, bicarbonate,bisulfate, butyrate, camphorate, camphorsulfonate, choline, citrate,cyclohexyl sulfamate, diethylenediamine, ethanesulfonate, fumarate,glutamate, glycolate, hemisulfate, 2-hydroxyethylsulfonate, heptanoate,hexanoate, hydrochloride, hydrobromide, hydroiodide, hydroxymaleate,lactate, malate, maleate, methanesulfonate (mesylate), meglumine,2-naphthalenesulfonate, nitrate, oxalate, pamoate, persulfate,phenylacetate, phosphate, diphosphate, picrate, pivalate, propionate,quinate, salicylate, stearate, succinate, sulfamate, sulfanilate,sulfate, tartrate, tosylate (p-toluenesulfonate), trifluoroacetate, andundecanoate. Non-toxic physiologically-acceptable salts are preferred,although other salts may be useful, such as in isolating or purifyingthe product.

The salts may be formed by conventional means, such as by reacting thefree base form of the product with one or more equivalents of theappropriate acid in a solvent or medium in which the salt is insoluble,or in a solvent such as water, which is removed in vacuo or by freezedrying or by exchanging the anions of an existing salt for another anionon a suitable ion-exchange resin.

The compounds of Formula I may have more than one chiral center, and itis to be understood that the application encompasses all individualstereoisomers, enantiomers and diastereoisomers and mixtures thereof.Thus, it is to be understood that, insofar as the compounds of Formula Ican exist in optically active or racemic forms by virtue of one or moreasymmetric carbon atoms, the application includes in its definition anysuch optically active or racemic form which possesses theabove-mentioned activity. The present application encompasses all suchstereoisomers having activity as herein defined.

Thus, throughout the specification, where reference is made to thecompound of Formula I it is to be understood that the term compoundincludes diastereoisomers, mixtures of diastereoisomers, and enantiomersthat are PARP1 inhibitors.

It is also to be understood that certain compounds of Formula I, andpharmaceutically salts thereof, can exist in solvated as well asunsolvated forms such as, for example, hydrated and anhydrous forms. Itis to be understood that the compounds herein encompass all suchsolvated forms. For the sake of clarity, this includes both solvated(e.g., hydrated) forms of the free form of the compound, as well assolvated (e.g., hydrated) forms of the salt of the compound.

Formula I as described herein is intended to encompass all isotopes ofits constituent atoms. For example, H (or hydrogen) includes anyisotopic form of hydrogen including ¹H, ²H (D), and ³H (T); C includesany isotopic form of carbon including ¹²C, ¹³C, and ¹⁴C; O includes anyisotopic form of oxygen including ¹⁶O, ¹⁷O and ¹⁸O; N includes anyisotopic form of nitrogen including ¹³N, ¹⁴N and ¹⁵N; F includes anyisotopic form of fluorine including ¹⁹F and ¹⁸F; and the like. In oneaspect, the compounds of Formula I include isotopes of the atoms coveredtherein in amounts corresponding to their naturally occurring abundance.However, in certain instances, it may be desirable to enrich one or moreatom in a particular isotope which would normally be present in a lowerabundance. For example, ¹H would normally be present in greater than99.98% abundance; however, in one aspect, a compound of any formulapresented herein may be enriched in ²H or ³H at one or more positionswhere H is present. In another aspect, when a compound of any formulapresented herein is enriched in a radioactive isotope, for example ³Hand ¹⁴C, the compound may be useful in drug and/or substrate tissuedistribution assays. It is to be understood that the present applicationencompasses all such isotopic forms.

The compounds of Formula I, or pharmaceutically acceptable saltsthereof, will normally be administered via the oral route in the form ofpharmaceutical preparations comprising the active ingredient or apharmaceutically acceptable salt or solvate thereof, or a solvate ofsuch a salt, in a pharmaceutically acceptable dosage form. Dependingupon the disorder and patient to be treated, the compositions may beadministered at varying doses.

The pharmaceutical formulations of the compound of Formula I describedabove may be prepared for oral administration, particularly in the formof tablets or capsules, and especially involving technologies aimed atfurnishing colon-targeted drug release (Patel, M. M. Expert Opin. DrugDeliv. 2011, 8 (10), 1247-1258).

The pharmaceutical formulations of the compound of Formula I describedabove may conveniently be administered in unit dosage form and may beprepared by any of the methods well-known in the pharmaceutical art, forexample as described in Remington's Pharmaceutical Sciences, 17th ed.,Mack Publishing Company, Easton, Pa., (1985).

Pharmaceutical formulations suitable for oral administration maycomprise one or more physiologically compatible carriers and/orexcipients and may be in solid or liquid form. Tablets and capsules maybe prepared with binding agents, fillers, lubricants and/or surfactants,such as sodium lauryl sulfate. Liquid compositions may containconventional additives such as suspending agents, emulsifying agentsand/or preservatives. Liquid compositions may be encapsulated in, forexample, gelatin to provide a unit dosage form. Solid oral dosage formsinclude tablets, two-piece hard shell capsules and soft elastic gelatin(SEG) capsules. Such two-piece hard shell capsules may be made forexample by filling a compound of Formula (I) into a gelatin orhydroxypropyl methylcellulose (HPMC) shell.

A dry shell formulation typically comprises of about 40% to 60% w/wconcentration of gelatin, about a 20% to 30% concentration ofplasticizer (such as glycerin, sorbitol or propylene glycol) and about a30% to 40% concentration of water. Other materials such aspreservatives, dyes, opacifiers and flavours also may be present. Theliquid fill material comprises a solid drug that has been dissolved,solubilized or dispersed (with suspending agents such as beeswax,hydrogenated castor oil or polyethylene glycol 4000) or a liquid drug invehicles or combinations of vehicles such as mineral oil, vegetableoils, triglycerides, glycols, polyols and surface-active agents.

Suitable daily doses of the compounds of Formula I, or apharmaceutically acceptable salt thereof, in therapeutic treatment ofhumans are about 0.0001-100 mg/kg body weight.

Oral formulations are preferred, particularly tablets or capsules whichmay be formulated by methods known to those skilled in the art toprovide doses of the active compound in the range of 0.1 mg to 1000 mg.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an X-ray powder diffractogram of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideForm B

FIG. 2 shows a DSC trace of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideForm B

FIG. 3 shows an X-ray powder diffractogram of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideForm D

FIG. 4 shows a single crystal structure of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideForm D (ORTEP50)

FIG. 5 shows an X-ray powder diffractogram of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideMSA salt Form C

FIG. 6 shows a DSC trace of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideMSA salt Form C

EXAMPLES

The compounds of the application will now be further explained byreference to the following non-limiting examples.

General Experimental Conditions

¹H NMR spectra were obtained using a Bruker 300 MHz, 400 MHz or 500 MHzspectrometer at 27° C. unless otherwise noted; chemical shifts areexpressed in parts per million (ppm, 5 units) and are referenced to theresidual mono-¹H isotopologue of the solvent (CHCl₃: 7.24 ppm; CHDCl₂:5.32 ppm; CD₃S(═O)CD₂H: 2.49 ppm). Coupling constants are given in unitsof hertz (Hz). Splitting patterns describe apparent multiplicities andare designated as s (singlet), d (doublet), t (triplet), q (quartet), m(multiplet) and br s (broad singlet). LC-MS was carried out using aWaters UPLC fitted with a Waters SQD mass spectrometer or ShimadzuLC-20AD LC-20XR LC-30AD with a Shimadzu 2020 mass spectrometer. Reportedmolecular ions correspond to [M+H]+ unless otherwise noted; formolecules with multiple isotopic patterns (Br, Cl, etc.) the reportedvalue is the one obtained for the lowest isotope mass unless otherwisespecified.

Flash chromatography was performed using straight phase flashchromatography on a SP1™ Purification system from Biotage™,CombiFlash®Rf from ISCO or on Gilson system from Thermo Fisher usingnormal phase silica FLASH+™ (40M, 25M or 12 M) or SNAP™ KP-SilCartridges (340, 100, 50 or 10), Flash Column silica-CS columns fromAgela, with C18-flash columns or standard flash chromatography. Ingeneral, all solvents used were commercially available and of analyticalgrade. Anhydrous solvents were routinely used for reactions. PhaseSeparators used in the examples are ISOLUTE® Phase Separator columns.The intermediates and examples named below were named using ACD/Name12.01 from Advanced Chemistry Development, Inc. (ACD/Labs). The startingmaterials were obtained from commercial sources or made via literatureroutes.

X-Ray Powder Diffraction (XRPD) Analysis

XRPD analysis was performed using a Bruker D8 diffractometer, which iscommercially available from Bruker AXS Inc™ (Madison, Wis.). The XRPDspectra were obtained by mounting a sample (approximately 10 mg) of thematerial for analysis on a single silicon crystal wafer mount (e.g., aBruker silicon zero background X-ray diffraction sample holder) andspreading out the sample into a thin layer with the aid of a microscopeslide. The sample was spun at 30 revolutions per minute (to improvecounting statistics) and irradiated with X-rays generated by a copperlong-fine focus tube operated at 40 kV and 40 mA with a wavelength of1.5406 angstroms (i.e., about 1.54 angstroms). The sample was exposedfor 1 second per 0.02 degree 2-theta increment (continuous scan mode)over the range 5 degrees to 40 degrees 2-theta in theta-theta mode. Therunning time was ˜15 min for D8.

XRPD 20 values may vary with a reasonable range, e.g., in the range±0.2° and that XRPD intensities may vary when measured for essentiallythe same crystalline form for a variety of reasons including, forexample, preferred orientation. Principles of XRPD are described inpublications, such as, for example, Giacovazzo, C. et al. (1995),Fundamentals of Crystallography, Oxford University Press; Jenkins, R.and Snyder, R. L. (1996), Introduction to X-Ray Powder Diffractometry,John Wiley & Sons, New York; and Klug, H. P. & Alexander, L. E. (1974),X-ray Diffraction Procedures, John Wiley and Sons, New York.

DSC Analysis

DSC analysis was performed on samples prepared according to standardmethods using a Q SERIES™ Q1000 DSC calorimeter available from TAINSTRUMENTS® (New Castle, Del.). A sample (approximately 2 mg) wasweighed into an aluminum sample pan and transferred to the DSC. Theinstrument was purged with nitrogen at 50 mL/min and data collectedbetween 22° C. and 300° C., using a dynamic heating rate of 10°C./minute. Thermal data was analyzed using standard software, e.g.,Universal V.4.5A from TA INSTRUMENTS®.

The following abbreviations are used: AcOH=acetic acid; aq=aqueous;BAST=Bis(2-methoxyethyl)aminosulfur Trifluoride; BoC₂O=di-tert-butyldecarbonate; Boc=t-butyloxycarbonyl; CDCl₃=deuterated chloroform;CD₃OD=deuterated methanol; CH₃NO2=nitromethane; DAST=Diethylaminosulfurtrifluoride; DCE=1,2-dichloroethane; DCM=dichloromethane;DDQ=2,3-Dichloro-5,6-dicyano-1,4-benzoquinone; DEA=diethylamine;DEAD=diethyl azodicarboxylate; Dess-martinperiodinane=1,1,1-Tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)-one;DIPEA=N,N-diisopropylethylamine; DMAP=2,6-dimethylaminopyridine;DMF=N,N-dimethylformamide; DMSO=dimethylsulfoxide; DMSO-d6=deuterateddimethylsulfoxide; DPPA=diphenyl phosphorazidate;dppf=1,1′-bis(diphenylphosphino)ferrocene; DIAD=Di-isopropyl(E)-diazene-1,2-dicarboxylate; DSC=differential scanning calorimetry;DTAD=Di-tert-butyl (E)-diazene-1,2-dicarboxylate; ee=enantiomericexcess; eq.=equivalent; ESI or ES=electrospray ionization; Et₂O=diethylether; EtOAc or EA=ethylacetate; EtOH=ethanol; FA=formic acid; Grubbscatalyst (1,3-Dimesitylimidazolin-2-ylidene)(tricyclohexylphosphine)ruthenium dichloride; h=hour(s);HATU=(dimethylamino)-N,N-dimethyl(3-oxido-1/−/−[1,2,3]triazolo[4,5-b]pyridinyl)methaniminiumhexafluorophosphate; HCl=hydrochloric acid; H₂O₂=hydrogen peroxide;HP=high pressure; IPA=isopropylalcohol; KF=potassium fluoride; LC=liquidchromatography; LiClO₄=lithium perchlorate; mmol=millimole;mCPBA=meta-chloroperoxybenzoic acid; MeOH=methanol; min=minute(s); MeCNor CH₃CN or ACN=acetonitrile; MeNO₂=nitromethane; MS=mass=spectrometery;NBS=N-Bromosuccinimide; NH4Cl=ammonium chloride;NMP=N-methyl-2-pyrrolidone; NMR=nuclear magnetic resonance;Pd/C=Palladium on carbon; Pd₂dba₃=Tris(dibenzylideneacetone)dipalladium(0); PdCl₂(dppf)=1,1′-bis(di-tert-butylphosphino)ferrocene palladiumdichloride; PE=Petroleum ether; PPh₃=Triphenylphosphine; rt=roomtemperature; Rt or RT=retention time; Ruphos PdG3=(2-Dicyclohexylphosphino-2′,6′-diisopropoxy-1,1′-biphenyl)[2-(2′-amino-1,1′-biphenyl)]palladium(II)methanesulfonate;Pd-PEPPSI™-IPent=Dichloro[1,3-bis(2,6-Di-3-pentylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium(II),[1,3-Bis(2,6-Di-3-pentylphenyl)imidazol-2-ylidene](3-chloropyridyl)dichloropalladium(II),[1,3-Bis(2,6-Di-3-pentylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium(II)dichloride; Xphos PdG2=Chloro(2-dicyclohexylphosphino-2′,4′,6′-triisopropyl-1,1′-biphenyl)[2-(2′-amino-1,1′-biphenyl)]palladium(II),X-Phos aminobiphenyl palladium chloride; CataCXiumA-Pd-G2=Chloro[(di(1-adamantyl)-N-butylphosphine)-2-(2-aminobiphenyl)]palladium(II);sat=saturated; SFC=supercritical fluid chromatography;T3P=2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphinane 2,4,6-trioxide;PPh3O=triphenylphosphine oxide;TBTU=2-(1H-benzo[d][1,2,3]triazol-1-yl)-1,1,3,3-tetramethylisouroniumtetrafluoroborate; TFA=trifluoroacetic acid; THF=tetrahydrofuran;TLC=thin layer chromatography; TMS=trimethylsilyl;Xantphos=4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; CBr4=Carbontetrabromide; HBr=hydrobromic acid; Cs2CO3=Cesium carbonate;MgSO4=Magnesium sulfate; NaHCO3=Sodium bicarbonate;DDQ=2,3-Dichloro-5,6-dicyano-1,4-benzoquinone; SOCl2=Thionyl chloride;DIBAL-H=Diisobutylaluminium hydride; NH4HCO3=Ammonium bicarbonate;BINAP=2,2′-bis(diphenylphosphino)-1,1′-binaphthyl; SM=starting material;CH₂Cl₂=dichloromethane; Et3N=triethylamine; HCO2H=formic acid;LCMS=liquid chromatography-mass spectrometry; N2=dinitrogen;Na2SO4=sodium sulfate; NH4CO3=ammonium carbonate; UV=ultraviolet; XPhosPdG2=Chloro(2-dicyclohexylphosphino-2′,4′,6′-triisopropyl-1,1′-biphenyl)[2-(2′-amino-1,1′-biphenyl)]palladium(II);Pd(OAc)2=palladium(II) acetate, ppt=precipitate.

Preparation of Examples

Intermediate 2: 1-bromo-4-fluoro-2-methyl-3-nitro-benzene

To a solution of 1-fluoro-3-methyl-2-nitro-benzene (10.7 g, 68.98 mmol)(intermediate 1) in TFA (50 mL) was added cone. H₂SO₄ (20 mL) at 0° C.slowly, followed by addition of NBS (13.50 g, 75.87 mmol) in portions.After addition, the mixture was stirred at room temperature for 4 h. Theresulting mixture was poured onto ice and the precipitate that formedcollected by filtration, washed with water and dried under vacuum togive 1-bromo-4-fluoro-2-methyl-3-nitro-benzene (intermediate 2) as awhite solid (14.80 g, 92%). 1H NMR (500 MHz, CHLOROFORM-d) 2.43 (3H, s),7.03 (1H, t), 7.68 (1H, dd).

Intermediate 3: 2-(4-bromo-3-methyl-2-nitro-anilino)propanoic Acid

A mixture of 1-bromo-4-fluoro-2-methyl-3-nitro-benzene (13.8 g, 58.97mmol) (intermediate 2), alanine (6.30 g, 70.76 mmol) and potassiumcarbonate (24.45 g, 176.90 mmol) in DMF (15 mL) was stirred at 100° C.for 5 h, then the temperature was raised to 110° C. and stirred for 5 h.The mixture was poured onto ice, quenched slowly with 1M HCl aq.solution (˜300 ml) at 0° C. gave a yellow suspension. The solid wascollected by filtration, washed with water and dried in a vacuum ovenfor 2 days at 50° C. to give2-(4-bromo-3-methyl-2-nitro-anilino)propanoic acid (14.03 g, 78%)(intermediate 3) as a yellow solid (some impurities present). 1H NMR(500 MHz, DMSO-d6) 1.39 (3H, d), 2.28 (3H, s), 4.20 (1H, quin), 6.12(1H, brd), 6.68 (1H, d), 7.58 (1H, d), 12.98 (1H, brs); m/z (ES⁺)[M+H]⁺=303.

Intermediate 4: methyl 2-(4-bromo-3-methyl-2-nitro-anilino)propanoate

To a solution of 2-(4-bromo-3-methyl-2-nitro-anilino)propanoic acid(14.9 g, 49.16 mmol) (intermediate 3) in MeOH (150 mL) was added thionylchloride (10.76 mL, 147.47 mmol) dropwise at 0° C. and the mixture wasstirred at rt for overnight. LCMS indicated full conversion. Thereaction mixture was quenched slowly with aq. sat. NaHCO₃ solution at 0°C. (˜300 ml) to give an orange suspension. The solid was collected byfiltration, washed with water and dried to yield the crude product (14.6g). The solid was purified on silica gel column (eluted with 0 to 25%ethyl acetate in hexanes), to give methyl2-(4-bromo-3-methyl-2-nitro-anilino)propanoate (intermediate 4) as abright orange solid (12.74 g, 82%). 1H NMR (500 MHz, CHLOROFORM-d) 1.52(3H, d), 2.43 (3H, s), 3.76 (3H, s), 4.14 (1H, quin), 5.83 (1H, brd),6.45 (1H, d), 7.48 (1H, d); m/z (ES⁺) [M+H]⁺=317.

Intermediate 5: 7-bromo-3,8-dimethyl-3,4-dihydro-1H-quinoxalin-2-one

To a stirred mixture of methyl2-(4-bromo-3-methyl-2-nitro-anilino)propanoate (11.6 g, 36.58 mmol)(intermediate 4), zinc (23.91 g, 365.77 mmol) and ammonium chloride(19.56 g, 365.77 mmol) in MeOH (100 mL) was added small ice piece at 0°C. (exothermic). The reaction mixture was then stirred for 15 min at 0°C. (ice bath). Water (2 mL) was added and the resulting mixture wasstirred at r.t for 15 min. The bright orange color disappeared. Themixture was filtered through filter paper, washed with methanol and thefiltrate was concentrated under vacuum. The residue was diluted withethyl acetate and washed with water followed by brine. Organic layer wasdried (anhydrous Na₂SO₄), filtered and concentrated to give a mixture ofmethyl 2-(2-amino-4-bromo-3-methyl-anilino)propanoate and7-bromo-3,8-dimethyl-3,4-dihydro-1H-quinoxalin-2-one (9.8 g).

To the solution of above solid in MeOH (100 mL) was added 2 ml of 4 MHCl in dioxanes at r.t and the mixture was stirred at r.t for 10 min.Another 100 ml methanol was added (to make free suspension) and theresulting suspension was stirred at r.t for 1 hr. The mixture wasdiluted with ether (˜200 ml), the solid was collected by filtration andwashed with ether. The filtrate was concentrated until a solidprecipitate and the solid was collected by filtration. This procedurewas repeated couple of times to yield first portion of the product 7.2g. The filtrate was concentrated and purified on silica gel column(eluted with 0 to 100% ethyl acetate in hexanes), and the productfraction were concentrated and resulting material was combined withabove material to give7-bromo-3,8-dimethyl-3,4-dihydro-1H-quinoxalin-2-one (9.10 g, 98%)(intermediate 5) as an off white solid. 1H NMR (500 MHz, DMSO-d6) 1.23(3H, d), 2.24 (3H, s), 3.68 (1H, q), 3.75 (br, 1H), (6.54 (1H, d), 7.00(1H, d), 9.77 (1H, s); m/z (ES⁺) [M+H]⁺=255.

Intermediate 6: 7-bromo-3B-dimethyl-1H-quinoxalin-2-one

DDQ (8.91 g, 39.24 mmol) was added to a suspension of7-bromo-3,8-dimethyl-3,4-dihydro-1H-quinoxalin-2-one (9.1 g, 35.67 mmol)(intermediate 5) in CH₂Cl₂ (400 mL) at room temperature and the mixturewas stirred for overnight. LCMS indicated clean conversion. Solvent wasremoved under reduced pressure, sat. NaHCO₃ (˜300 ml) solution was addedand the yellow suspension was stirred at rt for 4 h. The solid wascollected by filtration and washed with water. The solid was slurry insat. NaHCO₃ (100 ml) and stirred at rt for 1 h. The solid was filtered,washed with water followed ether and dried to yield7-bromo-3,8-dimethyl-1H-quinoxalin-2-one (7.29 g, 81%) (intermediate 6)as an off white solid. 1H NMR (500 MHz, DMSO-d6) 2.40 (3H, s), 2.50 (3H,s) (overlapped with DMSO-d6 peak), 7.32-7.65 (2H, m), 11.76 (1H, br s);m/z (ES⁺) [M+H]⁺=253.

Intermediate 7: 7-(hydroxymethyl)-3,8-dimethyl-1H-quinoxalin-2-one

A mixture of (tributylstannyl)methanol (1142 mg, 3.56 mmol),7-bromo-3,8-dimethyl-1H-quinoxalin-2-one (600 mg, 2.37 mmol)(intermediate 6) and Xphos Pd G2 (280 mg, 0.36 mmol) in 1,4-dioxane (40mL) was stirred at 80° C. for 18 h. The solvent was removed underreduced pressure and the residue was purified on silica gel column(eluted with 0 to 15% methanol in DCM) to yield7-(hydroxymethyl)-3,8-dimethyl-1H-quinoxalin-2-one (225 mg, 46%)(intermediate 7) as an off white solid. 1H NMR (500 MHz, DMSO-d6) 2.31(3H, s), 2.40 (3H, s), 4.58 (2H, d), 5.22 (1H, t), 7.33 (1H, d), 7.52(1H, d), 11.53 (1H, brs); m/z (ES⁺) [M+H]⁺=205.

Intermediate 8: 7-(bromomethyl)-3,8-dimethyl-1H-quinoxalin-2-one

7-(hydroxymethyl)-3,8-dimethyl-1H-quinoxalin-2-one (223 mg, 1.09 mmol)(intermediate 7) in HBr (15 ml, 132.59 mmol) (48 w % in water) wasstirred at 80° C. for 3.5 h. Solvent was removed under reduced pressure,diethyl ether was added to the residue, mixture was sonicated and thesolid was collected to yield7-(bromomethyl)-3,8-dimethyl-1H-quinoxalin-2-one (408 mg, 107%)(intermediate 8) as a yellow solid. 1H NMR (500 MHz, DMSO-d6) 2.36-2.45(6H, m), 4.83 (2H, s), 7.34 (1H, d), 7.53 (1H, d), 11.63 (1H, br s); m/z(ES⁺) [M+H]⁺=267, 269.

Example 1:5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide

To the suspension of 7-(bromomethyl)-3,8-dimethyl-1H-quinoxalin-2-one,HBr (37 mg, 0.10 mmol) (intermediate 8) was added ACN (5 ml),6-fluoro-N-methyl-5-(piperazin-1-yl)picolinamide, 2HCl (31.5 mg, 0.10mmol) (intermediate 32) and DIPEA (79 μl, 0.45 mmol) and the reactionmixture was stirred at 70° C. for 1 h to give a light yellow suspension.The suspension was cooled to rt, 1 drop of water was added, the solidwas collected by filtration, washed with acetonitrile three time anddried to yield5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide(0.016 g, 33%) (example 1) as a yellow solid. 1H NMR (500 MHz, DMSO-d6)2.07 (3H, brs), 2.42 (3H, brd), 2.56 (4H, br s), 2.76 (3H, br s), 3.14(4H, br s), 3.61 (2H, br s), 7.23 (1H, br d), 7.42-7.67 (2H, m), 7.83(1H, br d), 8.38 (1H, br s), 11.13-11.97 (1H, m); m/z (ES⁺) [M+H]⁺=425.

Example 2:5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

To a suspension of 7-(bromomethyl)-3,8-dimethylquinoxalin-2(1H)-one, HBr(240 mg, 0.69 mmol) (intermediate 8),N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide, 2HCl (202 mg, 0.69mmol) (intermediate 31) in acetonitrile (13 mL) was added DIPEA (0.723mL, 4.14 mmol) and the resulting mixture was stirred at 70° C. for 3 h.The mixture was concentrated and purified on reverse phase (C18 column,eluted with 0 to 100% ACN/water (0.2% ammonium hydroxide)) to yield theproduct as a brown solid. The solid was suspended in a mixture was DCMand MeOH (2:1), concentrated to remove DCM and the solid was filteredand washed with methanol. The solid was suspended in ACN (3 ml), 0.8 mlof 1M HCl in water was added, diluted with water (˜3 ml) and lyophilizedto dryness to yield the HCl salt of the product5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(0.033 g, 11%) (example 2). 1HNMR (500 MHz, DMSO-d6) 2.45 (3H, s), 2.54(3H, s), 2.81 (3H, brd), 3.24-3.56 (6H, m), 3.88-4.02 (2H, m), 4.54 (2H,br s), 7.48-7.71 (3H, m), 7.97 (1H, br d), 8.33 (1H, br d), 8.59 (1H, brs), 11.28 (1H, br s), 11.48-11.95 (1H, m); m/z (ES⁺) [M+H]⁺=407.

Example 3:6-chloro-5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

HBr in AcOH (2 mL, 0.18 mmol) (33 wt %) was added to the solution7-(hydroxymethyl)-3,8-dimethyl-1H-quinoxalin-2-one (36 mg, 0.18 mmol)(intermediate 7) in NMP (2 mL). The resulting mixture was stirred at100° C. for 1 hour. The solvent was removed under reduced pressure.DIPEA (0.25 mL, 1.43 mmol) was added to a solution of6-chloro-N-methyl-5-(piperazin-1-yl)picolinamide (48 mg, 0.19 mmol)(intermediate 30) in NMP (2 mL). The resulting mixture was stirred at100° C. for 18 hours. The crude product was purified by preparative HPLC(column: YMC-Actus Triart C18, 30*250, 5 μm; Mobile Phase A: Water(0.05% NH₃H₂O), Mobile Phase B: ACN; Flow rate: 60 mL/min; Gradient: 41B to 61 B in 7 min; 254; 220 nm. Fractions containing the desiredcompound were evaporated to dryness to yield6-chloro-5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(33.0 mg, 42%) (example 3) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.41 (3H, s), 2.43 (3H, s), 2.54-2.62 (4H, m), 2.78 (3H, d), 3.05-3.11(4H, m), 3.62 (2H, s), 7.24 (1H, d), 7.51 (1H, d), 7.65 (1H, d), 7.92(1H, d), 8.41-8.45 (1H, m), 11.56 (1H, s); m/z (ES⁺) [M+H]⁺=441.

Example 4:5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

HBr in AcOH (2 mL, 12.15 mmol) (33 wt %) was added to the solution of7-(hydroxymethyl)-3,8-dimethyl-1H-quinoxalin-2-one (43 mg, 0.21 mmol)(intermediate 7) in NMP (2 mL). The resulting mixture was stirred at 80°C. for 1 hour. The solvent was removed under reduced pressure. To thesolution of the resulting solid in NMP (3 mL) was added DIPEA (0.25 mL,1.43 mmol) and N,6-dimethyl-5-(piperazin-1-yl)picolinamide (42 mg, 0.18mmol) (intermediate 33). The resulting mixture was stirred at 100° C.for 18 hours. The crude product was purified by preparative HPLC(Column: YMC-Actus Triart C18, 30*250, 5 μm; using water in acetonitrile(0.05% NH₄OH. Fractions containing the desired compound were evaporatedto dryness to afford5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 4) (18.40 mg, 24%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.40 (3H, s), 2.43 (3H, s), 2.48 (3H, s), 2.55-2.63 (4H, m), 2.79 (3H,d), 2.87-2.94 (4H, m), 3.62 (2H, s), 7.24 (1H, d), 7.46 (1H, d), 7.51(1H, d), 7.78 (1H, d), 8.39-8.44 (1H, m), 11.56 (1H, s); m/z (ES⁺)[M+H]⁺=421.

Intermediate 10: methyl 5-bromo-6-fluoro-pyridine-2-carboxylate

A dried flask was charged with methyl 5-bromopicolinate (intermediate 9)(24 g, 111.09 mmol) in acetonitrile (300 ml), silver(II) fluoride (50 g,342.78 mmol) was added, the mixture was stirred at r.t for 1 day underN₂. LCMS indicated about 70% conversion. Another batch of AgF2 (16 g)was added and the resulting mixture was continued to stir at rt forovernight. The mixture was filtered through ceilite, washed withacetonitrile followed by DCM and the filtrate was concentrated to yielda light brown solid. The residue was partitioned between DCM and sat.NH₄Cl solution which gave a white suspension. The solid was filtered offand discarded. The filtrate was transferred to separating funnel,organic layer was separated, and the aqueous layer was extracted withethyl acetate (150 ml×3). The organics were combined, dried (anhydrousNa₂SO₄), filtered and concentrated until solid precipitates out. Thesolid was collected by filtration, washed with ether, dried to yield aflaky off white solid. The combined filtrate was concentrated again andthe solid was collected by filtration to give combined 19.96 g ofproduct. The rest of the filtrate was concentrated and purified onsilica gel column (eluted with 0 to 25% ethyl acetate in hexanes) toyield a second portion of the desired product as a white flaky solid 3.5g. All the material was combined to yield methyl5-bromo-6-fluoro-pyridine-2-carboxylate (23.46 g, 90%) (intermediate10). 1H NMR (500 MHz, DMSO-d6) 3.89 (3H, s), 7.93 (1H, d), 8.51 (1H, t);m/z (ES⁺) [M+H]⁺=234.

Intermediate 11: tert-butyl4-(2-fluoro-6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate

A mixture of tert-butyl piperazine-1-carboxylate (28.0 g, 150.37 mmol),methyl 5-bromo-6-fluoro-pyridine-2-carboxylate (intermediate 10) (23.46g, 100.25 mmol), RuPhos Pd G3 (5.45 g, 6.52 mmol) and Cs₂CO₃ (82 g,250.61 mmol) in 1,4-dioxane (400 mL) was stirred at 80° C. for overnightunder N2. The reaction mixture was diluted with water (250 ml) andextracted with ethyl acetate (250 ml). The organic layer was washed withbrine, the water layer was extracted with ethyl acetate (100 ml×1), theorganics were dried (anhydrous Na₂SO₄), filtered and concentrated, theresidue was purified on silica gel column (eluted with 0 to 50% ethylacetate in hexanes) to yield the product as a yellow solid, the solidwas recrystallized from ethyl acetate/hexanes, filtered, washed withhexanes, dried to yield the product as a crystalline white solid (24.8g); The filtrate was concentrated and repurified on silica gel column toyield more of the product 1.9 g. In total yield tert-butyl4-(2-fluoro-6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate(intermediate 11) (26.7 g, 78%). 1H NMR (500 MHz, CHLOROFORM-d) 1.51(9H, s), 3.12-3.28 (4H, m), 3.48-3.67 (4H, m), 3.98 (3H, s), 7.27 (1H,d), 7.99 (1H, dd); m/z (ES⁺) [M+H]⁺=340.

Intermediate 12: methyl 6-fluoro-5-piperazin-1-yl-pyridine-2-carboxylate

To a mixture of tert-butyl4-(2-fluoro-6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate (1.9 g,5.60 mmol) (intermediate 11) in MeOH (10 mL) was added HCl 4 M indioxane (10 ml, 40.00 mmol) at rt and the resulting mixture was stirredat r.t for 1 h. The mixture was diluted with ether, the solid wascollected by filtration, washed with ether and dried under vacuum toyield methyl 6-fluoro-5-piperazin-1-yl-pyridine-2-carboxylate (1.360 g,78%) (intermediate 12) as a white solid. 1H NMR (500 MHz, DMSO-d6) 3.24(4H, br s), 3.46 (4H, br s), 3.84 (3H, s), 7.65 (1H, br t), 7.94 (1H, brd), 9.43 (2H, br s); m/z (ES⁺) [M+H]⁺=240.

Intermediate 13: methyl5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-pyridine-2-carboxylate

7-(hydroxymethyl)-3,8-dimethylquinoxalin-2(1H)-one (223 mg, 1.09 mmol)(intermediate 7) in HBr (15 ml, 132.59 mmol) (48 w % in water) wasstirred at 80° C. for 3.5 h. The solvent was removed under reducedpressure, DCM was added to the residue and concentrated to yield7-(bromomethyl)-3,8-dimethylquinoxalin-2(1H)-one as a yellow solid.

To the solution of above solid in acetonitrile (20 ml) was added methyl6-fluoro-5-piperazin-1-yl-pyridine-2-carboxylate, 2HCl (260 mg, 0.83mmol) (intermediate 12), and DIPEA (1.907 ml, 10.92 mmol) at rt and thereaction mixture was stirred at 70° C. for 2 h. The mixture was cooledto rt, 0.5 ml of water was added and the solid was collected byfiltration and washed with acetonitrile. The solid was dried to yield anoff white solid as methyl5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-pyridine-2-carboxylate(0.371 g, 80%) (intermediate 13). 1H NMR (500 MHz, DMSO-d6) 2.42 (6H,m), 2.52-2.59 (4H, m), 3.20 (4H, brd), 3.61 (2H, s), 3.82 (3H, s), 7.23(1H, d), 7.41-7.59 (2H, m), 7.91 (1H, d), 11.55 (1H, s); m/z (ES⁺)[M+H]⁺=426.

Example 5:5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-pyridine-2-carboxamide

A sealed 40 ml vial was charged with methyl5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-pyridine-2-carboxylate(360 mg, 0.85 mmol) (intermediate 13) and ammonia (15 ml, 105.00 mmol, 7N in methanol) and the mixture was stirred at 50° C. for overnight. LCMSindicated there was still some starting material left. The mixture wasconcentrated, 10 ml of 7 N ammonia in methanol was added to the solidand the mixture was stirred at 50° C. for 4 h gave a white suspension.The solid was collected by filtration, washed with hexanes and dried toyield5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-pyridine-2-carboxamide(example 5) (340 mg, 98%) as a white solid. 1H NMR (500 MHz, DMSO-d6)2.40 (3H, s), 2.43 (3H, s), 2.56 (4H, br s), 3.14 (4H, br s), 3.61 (2H,s), 7.23 (1H, d), 7.46 (1H, br s), 7.48-7.58 (2H, m), 7.76 (1H, br s),7.84 (1H, br d), 11.11-11.70 (1H, m); m/z (ES⁺) [M+H]⁺=411.

Intermediate 15: tert-butyl4-(6-methoxycarbonyl-2-methyl-3-pyridyl)piperazine-1-carboxylate

A 40 mL vial fitted with septa cap was charged with methyl5-bromo-6-methylpicolinate (intermediate 14) (2 g, 8.69 mmol),tert-butyl piperazine-1-carboxylate (3.24 g, 17.39 mmol), Cs₂CO₃ (5.66g, 17.39 mmol) and Ruphos Pd G3 (0.727 g, 0.87 mmol). The reaction vialwas evacuated under vacuum and filled with nitrogen. 1,4-dioxane (20 mL)was added and the reaction vial was placed in a heating block pre-heatedto 80° C. and stirred for 16 h. The reaction mixture was cooled, dilutedwith water and extracted with ethyl acetate, the organic layer waswashed with brine, dried over anhydrous Na2SO₄ and concentrated. Theresidue was purified on silica gel column (eluted with 0 to 50% ethylacetate in hexanes) to yield tert-butyl4-(6-methoxycarbonyl-2-methyl-3-pyridyl)piperazine-1-carboxylate(intermediate 15) (2.090 g, 72%) as a light-yellow solid. 1H NMR (500MHz, DICHLOROMETHANE-d2) 1.49 (9H, s), 2.59 (3H, s), 2.88-3.00 (4H, m),3.55-3.65 (4H, m), 3.92 (3H, s), 7.32 (1H, d), 7.92 (1H, d); m/z (ES⁺)[M+H]⁺=336.

Intermediate 16: methyl 6-methyl-5-piperazin-1-yl-pyridine-2-carboxylate

4 M solution of hydrogen chloride in 1,4-dioxane (31.2 ml, 124.63 mmol)was added to a stirred solution of tert-butyl4-(6-(methoxycarbonyl)-2-methylpyridin-3-yl)piperazine-1-carboxylate(intermediate 15) (4.18 g, 12.46 mmol) in DCM (30 mL) and the resultingsolution was stirred at rt for 18 h. Solvent was removed under vacuum,the resulting solid was slurried in diethyl ether and solid wascollected by filtration to give methyl6-methyl-5-piperazin-1-yl-pyridine-2-carboxylate (intermediate 16) (3.80g, 99%) as a light-yellow solid; m/z (ES⁺) [M+H]⁺=236.

Intermediate 18: methyl5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxylate

Triphenylphosphine (1.584 g, 6.04 mmol) (4.4 g added, calculated basedon PPh3 loading of 1.6 mmol/g) was added to a stirred slurry of8-fluoro-7-(hydroxymethyl)-3-methylquinoxalin-2(1H)-one (419 mg, 2.01mmol) (intermediate 17) and perbromomethane (1.335 g, 4.03 mmol) in DCM(40 mL) at rt. The resulting mixture was stirred for 1 h. Reactionmixture was filtered, washed with DCM and THF and the filtrate wasconcentrated under vacuum to yield7-(bromomethyl)-8-fluoro-3-methylquinoxalin-2(1H)-one as a light yellowsolid.

To the slurry of above freshly prepared7-(bromomethyl)-8-fluoro-3-methylquinoxalin-2(1H)-one in acetonitrile(25 mL) was added methyl6-methyl-5-piperazin-1-yl-pyridine-2-carboxylate, 2HCl (590 mg, 1.91mmol) (intermediate 16), and N-ethyl-N-isopropylpropan-2-amine (1754 μl,10.07 mmol) and the reaction was heated to 70° C. for 1 h. The reactionmixture was cooled to rt, concentrated, and quenched with sat. aqueousNaHCO₃ solution and stirred for 1 h. Solid was isolated by filtrationand washed with water. The crude solid was purified on silica columnchromatography using 0-10% MeOH in DCM to yield methyl5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxylate(intermediate 18) (0.263 g, 31%). 1H NMR (500 MHz, DMSO-d6) 2.40-2.49(6H, m), 2.62 (4H, br s), 2.97 (4H, br s), 3.72 (2H, s), 3.83 (3H, s),7.30 (1H, t), 7.44 (1H, d), 7.52 (1H, d), 7.85 (1H, d), 12.45 (1H, brs);19F NMR (471 MHz, DMSO-d6) −135.54 (1F, s); m/z (ES⁺) [M+H]⁺=426.

Example 6:5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxamide

7 N ammonia in methanol (16.47 ml, 115.26 mmol) was added to methyl5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxylate(intermediate 18) (0.2452 g, 0.58 mmol) in a 40 mL scintillation vial,sealed and stirred at rt for 18 h. Additional 7 N NH₃ solution (15 mL)was added to the reaction mixture and stirred at 50° C. for overnight.The reaction was concentrated under vacuum, slurry in 5 mL MeOH. Solidwas filtered off, washed with methanol and dried to yield5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxamide(Example 6) (0.151 g, 64%) as an off-white solid. 1H NMR (500 MHz,DMSO-d6) 2.42 (3H, s), 2.45-2.49 (3H, m), 2.52-2.69 (4H, m), 2.94 (4H,brs), 3.71 (2H, s), 7.29 (1H, t), 7.40-7.54 (3H, m), 7.77-7.84 (2H, m),12.43 (1H, br s); 19F NMR (471 MHz, DMSO-d6) −135.53 (1F, s); m/z (ES⁺)[M+H]⁺=411.

Intermediate 19: methyl5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxylate

7-(hydroxymethyl)-3,8-dimethylquinoxalin-2(1H)-one (intermediate 7) (223mg, 1.09 mmol) in HBr (15 ml, 132.59 mmol) (48 w % in water) was stirredat 80° C. for 4 h. Solvent was removed under reduced pressure, DCM wasadded to the residue, mix was sonicated and concentrated to yield7-(bromomethyl)-3,8-dimethylquinoxalin-2(1H)-one as a yellow solid.

To the slurry of above in acetonitrile (20 ml) was added methyl6-methyl-5-piperazin-1-yl-pyridine-2-carboxylate, 2HCl (intermediate 16)(337 mg, 1.09 mmol), and DIPEA (1.907 ml, 10.92 mmol). The reactionmixture was stirred at 70° C. for 2 h gave clear solution. The resultingmixture was cooled to r.t, half of the solvent was removed, 0.5 ml ofwater was added. The solid was collected by filtration, washed withacetonitrile and dried to yield a yellow solid. This solid was purifiedon silica gel column (eluted with 0 to 20% methanol in DCM) to Yieldmethyl5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxylate(intermediate 19) (213 mg, 46%) as an off white solid. 1H NMR (500 MHz,DMSO-d6) 2.41 (3H, s), 2.43 (3H, s), 2.47 (3H, s), 2.58 (4H, brs), 2.95(4H, brs), 3.63 (2H, s), 3.82 (3H, s), 7.24 (1H, d), 7.43 (1H, d), 7.51(1H, d), 7.84 (1H, d), 11.55 (1H, s). m/z (ES⁺) [M+H]⁺=422.

Example 7:5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxamide

A sealed 40 ml vial was charged with methyl5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxylate(intermediate 19) (210 mg, 0.50 mmol) and ammonia (15 ml, 105.00 mmol, 7N in methanol) and the reaction was stirred at 50° C. for overnight.Reaction was not complete. The mixture was concentrated, 10 ml of 7 Nammonia in methanol was added to this solid. Vial was capped and stirredat 50° C. for 4 h to give a white suspension. The mixture was cooled tort, the solid was collected by filtration, washed with hexanes and driedto yield5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxamide(example 7) (191 mg, 94%) as a white solid. 1H NMR (500 MHz, DMSO-d6)2.41 (3H, s), 2.44 (3H, s), 2.49 (3H, s), 2.58 (4H, brs), 2.92 (4H,brs), 3.63 (2H, br s), 7.24 (1H, br d), 7.42 (1H, br s), 7.46 (1H, brd), 7.51 (1H, br d), 7.79 (2H, br d), 10.53-11.23 (1H, m); m/z (ES⁺)[M+H]⁺=407.

Intermediate 21: methyl 2-aminobutanoate

A slurry of 2-aminobutanoic acid (intermediate 20) (5 g, 48.49 mmol) inmethanol (35 mL) was cooled in an ice bath. Thionyl chloride (11 mL,150.72 mmol) was added dropwise to the above mixture at 0° C. Thereaction was allowed to warm to rt and stirred overnight. The clearsolution was concentrated to dryness to obtain a residue. The resultingsolid was suspended into ether, filtered, washed with ether and dried toyield methyl 2-aminobutanoate.HCl (intermediate 21) (7.35 g, 99%) as awhite solid as HCl salt. 1H NMR (500 MHz, DMSO-d6) 0.92 (3H, t),1.76-1.93 (2H, m), 3.75 (3H, s), 3.95-4.05 (1H, m), 8.53 (3H, br s).

Intermediate 23: methyl 2-(4-bromo-3-chloro-2-nitro-anilino)butanoate

A flask was charged with methyl 2-aminobutanoate, HCl (intermediate 21)(1.811 g, 11.79 mmol), 1-bromo-2-chloro-4-fluoro-3-nitrobenzene(intermediate 22) (2.0 g, 7.86 mmol) in 1,4-dioxane (30 mL), DIPEA (8.24mL, 47.16 mmol) was added and the mixture was stirred at 105° C. for 24h. The mixture was concentrated, and the residue was purified on silicagel column (eluted with 0 to 50% ethyl acetate in hexanes) to yieldmethyl 2-(4-bromo-3-chloro-2-nitro-anilino)butanoate (intermediate 23)(2.100 g, 76%) as a bright yellow oil, turned into yellow solid afterstanding. 1H NMR (500 MHz, CHLOROFORM-d) 0.99 (3H, t), 1.78-1.89 (1H,m), 1.91-2.02 (1H, m), 3.77 (3H, s), 4.04 (1H, q), 5.63 (1H, br d), 6.55(1H, d), 7.52 (1H, d); m/z (ES⁺) [M+H]⁺=351.

Intermediate 24:7-bromo-8-chloro-3-ethyl-3,4-dihydro-1H-quinoxalin-2-one

Sodium dithionite (3.05 g, 17.49 mmol) was added to a stirred mixture ofmethyl 2-(4-bromo-3-chloro-2-nitro-anilino)butanoate (intermediate 23)(2.05 g, 5.83 mmol) in DMSO (50 mL) and the mixture was stirred at 120°C. for 3 h. The mixture was quenched with water and extracted with ethylacetate (50 ml×2). The organic layer was dried (anhydrous Na2SO₄),filtered, concentrated and the residue was purified on silica gel column(0 to 55% ethyl acetate in hexanes) to yield peak 1 as7-bromo-8-chloro-3-ethyl-1H-quinoxalin-2-one (intermediate 25) (0.319 g,19%) as a light yellow solid. 1H NMR (500 MHz, METHANOL-d4) 1.31 (3H,t), 2.89 (2H, q), 7.56-7.67 (2H, m); m/z (ES⁺) [M+H]⁺=287, 289

and peak 2 as 7-bromo-8-chloro-3-ethyl-3,4-dihydro-1H-quinoxalin-2-one(intermediate 24) (0.895 g, 53%) as a yellow oil which turned into ayellow solid upon standing. 1H NMR (500 MHz, CHLOROFORM-d) 1.04 (3H, t),1.75-1.84 (1H, m), 1.85-1.93 (1H, m), 3.89 (1H, dd), 6.51 (1H, d), 7.12(1H, d), 7.82 (1H, br s). m/z (ES⁺) [M+H]⁺=289, 291.

Intermediate 25: 7-bromo-8-chloro-3-ethyl-1H-quinoxalin-2-one

DDQ (772 mg, 3.40 mmol) was added to a mixture of7-bromo-8-chloro-3-ethyl-3,4-dihydro-1H-quinoxalin-2-one (intermediate24) (895 mg, 3.09 mmol) in 1,4-dioxane (20 mL) at rt and the resultingsuspension was stirred at rt for 3 h. LCMS indicated full conversion.The solvent was removed under reduced pressure and the residue wastreated with sat. NaHCO₃ solution, stirred at rt for 2 h. Solid wascollected by filtration, washed with sat. NaHCO₃ solution, water anddried to yield 7-bromo-8-chloro-3-ethyl-1H-quinoxalin-2-one(intermediate 25) (780 mg, 88%) as an off white solid. 1H NMR (500 MHz,METHANOL-d4) 1.31 (3H, t), 2.89 (2H, q), 7.56-7.67 (2H, m); m/z (ES⁺)[M+H]⁺=287, 289.

Intermediate 26: 8-chloro-3-ethyl-7-vinyl-1H-quinoxalin-2-one

A mixture of 7-bromo-8-chloro-3-ethyl-1H-quinoxalin-2-one (intermediate25) (1.05 g, 3.65 mmol), tributyl(vinyl)stannane (1.737 g, 5.48 mmol)and Pd(PPh₃)₄ (0.422 g, 0.37 mmol) in toluene (50 mL) was stirred at110° C. under N₂ for 2 h. LCMS indicated about 44% starting materialleft. The mixture was continued to stir at this temperature for 4.5 hand then at 80° C. for overnight. The mixture was concentrated, purifiedon silica gel column (eluted with 0 to 100% ethyl acetate in hexanes) toyield low soluble desired product8-chloro-3-ethyl-7-vinyl-1H-quinoxalin-2-one (intermediate 26) (0.850 g,99%) as a light yellow solid, m/z (ES⁺) [M+H]⁺=235 (the product wascontaminated by PPh₃O).

Intermediate 27: 5-chloro-2-ethyl-3-oxo-4H-quinoxaline-6-carbaldehyde

Osmium tetroxide in H₂O (0.568 mL, 0.07 mmol) was added to a solution of8-chloro-3-ethyl-7-vinyl-1H-quinoxalin-2-one (intermediate 26) (850 mg,3.62 mmol), 2,6-lutidine (0.844 mL, 7.24 mmol) and sodium periodate(3099 mg, 14.49 mmol) in THF (50 mL)/water (10 mL)/tert-butanol (3.46mL, 36.22 mmol) and stirred at rt for overnight gave a yellowsuspension. Reaction was concentrated, partitioned between water, sat.NH₄Cl solution and DCM and the layers were separated. The aqueous layerwas extracted with DCM and the combined organic layer was dried(anhydrous Na₂SO₄), filtered and concentrated. The residue was purifiedon silica gel column (eluted with 0 to 50% ethyl acetate in hexanes) toyield 5-chloro-2-ethyl-3-oxo-4H-quinoxaline-6-carbaldehyde (intermediate27) (808 mg, 94%) as a light yellow solid. 1H NMR (500 MHz,CHLOROFORM-d) 1.34-1.42 (3H, m), 3.03 (2H, q), 7.88 (2H, d), 8.99-9.38(1H, m), 10.54 (1H, s); m/z (ES⁺) [M+H]⁺=237.

Intermediate 28: 8-chloro-3-ethyl-7-(hydroxymethyl)-1H-quinoxalin-2-one

5-chloro-2-ethyl-3-oxo-4H-quinoxaline-6-carbaldehyde (intermediate 27)(808 mg, 3.41 mmol) in MeOH (30 mL) was cooled to 0° C. and sodiumborohydride (1292 mg, 3.41 mmol) (10 wt % on basic alumina) was added inone portion. The reaction mixture was continued to stir at 0° C. for 40min. LCMS indicated some starting material remaining. Another 213 mgs ofthe NaBH₄ (10 wt %) was added to this mixture and stirring was continuedat 0° C. for 10 min. To the mixture was added 1 ml of water,concentrated and the residue was purified on silica gel column (elutedwith 0 to 25% methanol in DCM) to yield8-chloro-3-ethyl-7-(hydroxymethyl)-1H-quinoxalin-2-one (intermediate 28)(625 mg, 77%) (contaminated by 26% of over reduced side product). 1H NMR(500 MHz, METHANOL-d4) 1.27-1.34 (3H, m), 2.91 (2H, q), 4.79-4.82 (2H,m), 7.54 (1H, d), 7.75 (1H, d); m/z (ES⁺) [M+H]⁺=239.

Intermediate 29: 7-(bromomethyl)-8-chloro-3-ethyl-1H-quinoxalin-2-one

carbon tetrabromide (1612 mg, 4.86 mmol) was added in one portion to asolution of 8-chloro-3-ethyl-7-(hydroxymethyl)-1H-quinoxalin-2-one(intermediate 28) (580 mg, 2.43 mmol) and triphenylphosphine (1275 mg,4.86 mmol) in CH₂Cl₂ (40 mL) at 0° C. and the mixture was stirred at 0°C. for 1 h. LCMS indicated full conversion. The solvent was removedunder reduced pressure and the residue was purified on silica gel column(eluted with 0 to 50% ethyl acetate in hexanes) to yield pure7-(bromomethyl)-8-chloro-3-ethyl-1H-quinoxalin-2-one (intermediate 29)(200 mgs, 27%) as a white solid. 1H NMR (500 MHz, DMSO-d6) 1.22 (3H, t),2.83 (2H, q), 4.85 (2H, s), 7.51 (1H, d), 7.71 (1H, d), 11.89 (1H, brs); m/z (ES⁺) [M+H]⁺=301, 303.

Example 8:6-chloro-5-[4-[(5-chloro-2-ethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

DIPEA (0.058 mL, 0.33 mmol) was added to a stirred suspension of7-(bromomethyl)-8-chloro-3-ethyl-1H-quinoxalin-2-one (intermediate 29)(25 mg, 0.08 mmol) and6-chloro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide, 2HCl(intermediate 30) (27.2 mg, 0.08 mmol) in acetonitrile (4 mL) and theresulting mixture was stirred at 70° C. for 1.5 h gave a suspension.LCMS indicated full conversion. The solvent was removed under reducedpressure and submitted to analytical purification group which afterpurification gave6-chloro-5-[4-[(5-chloro-2-ethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 8) (24.00 mg, 61%) as a yellow solid. Purification conditions(achiral): column (Xbridge C18 19 mm×100 mm 5 μm, mobile phase A: H₂Owith 0.2% NH₄OH PH 10, mobile phase B: Acetonitrile; Gradient B %:13-95% B over 8 min; Flow rate: 20 ml/min; Concentration: 35 mg/ml inDMSO; Loading (mg/injection): 15; Column temperature: room temperature.1H NMR (500 MHz, DMSO-d6) 1.23 (3H, t), 2.66 (4H, br s), 2.76-2.92 (5H,m), 3.13 (4H, brs), 3.77 (2H, s), 7.44 (1H, d), 7.69 (2H, dd), 7.94 (1H,d), 8.43 (1H, q), 10.75-11.45 (1H, m); m/z (ES⁺) [M+H]⁺=475.

Example 9:5-[4-[(5-chloro-2-ethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide

DIPEA (0.116 mL, 0.66 mmol) was added to a stirred suspension of6-fluoro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide, 2HCl(intermediate 32) (51.6 mg, 0.17 mmol) and7-(bromomethyl)-8-chloro-3-ethylquinoxalin-2(1H)-one (intermediate 29)(50 mg, 0.17 mmol) in acetonitrile (4 mL) and the resulting mixture wasstirred at 70° C. for 1.5 h. LCMS indicated full conversion. The solventwas removed under reduced pressure and the residue was purified onsilica gel column (eluted with 0 to 20% methanol in DCM) to give mixtureof product and PPh3O. Material was submitted for analytical group forpurification which after purification yield5-[4-[(5-chloro-2-ethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide(example 9) (47.0 mg, 62%) as a yellow solid. Purification conditions(achiral): column (Xbridge C18 19 mm×100 mm 5 μm, mobile phase A: H₂Owith 0.2% NH₄OH PH 10, mobile phase B: Acetonitrile; Gradient B %:13-95% B over 8 min; Flow rate: 20 ml/min; Concentration: 35 mg/ml inDMSO; Loading (mg/injection): 15; Column temperature: room temperature.

1H NMR (500 MHz, DMSO-d6) 1.22 (3H, t), 2.63 (4H, brs), 2.76 (3H, d),2.82 (2H, q), 3.19 (4H, brs), 3.75 (2H, s), 7.43 (1H, d), 7.52-7.64 (1H,m), 7.70 (1H, d), 7.84 (1H, d), 8.39 (1H, q), 11.17-11.55 (1H, m); m/z(ES⁺) [M+H]⁺=459.

Example 10:5-[4-[(5-chloro-2-ethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

DIPEA (0.081 mL, 0.46 mmol) was added to a stirred suspension ofN-methyl-5-(piperazin-1-yl)picolinamide, 2HCl (intermediate 31) (34.0mg, 0.12 mmol) and 7-(bromomethyl)-8-chloro-3-ethylquinoxalin-2(1H)-one(intermediate 29) (35 mg, 0.12 mmol) in acetonitrile (4 mL) and theresulting mixture was stirred at 70° C. for 1.5 h. LCMS indicated fullconversion. The solvent was removed under reduced pressure and theresulting residue was submitted to analytical group for purificationwhich after purification gave5-[4-[(5-chloro-2-ethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 10) (13.00 mg, 20%) as a white solid. Purification conditions(achiral) column (Xbridge C18 19 mm×100 mm 5 μm, mobile phase A: H₂Owith 0.2% NH₄OH PH 10, mobile phase B: Acetonitrile; Gradient B % 13-95%B over 8 min; Flow rate: 20 ml/min; Concentration: 35 mg/ml in DMSO;Loading (mg/injection): 15; Column temperature: room temperature. 1H NMR(500 MHz, DMSO-d6) 1.24 (3H, t), 2.79 (3H, d), 2.86 (2H, q), 3.22-3.37(8H, m, merged into water peak), 4.39-4.65 (2H, m), 7.46 (1H, dd), 7.57(1H, br d), 7.79-7.90 (2H, m), 8.32 (1H, d), 8.43 (1H, br d),11.87-12.21 (1H, m). m/z (ES⁺) [M+H]⁺=441.

Example11:5-[4-[(5-chloro-2-ethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

DIPEA (0.111 mL, 0.64 mmol) was added to a stirred suspension ofN,6-dimethyl-5-piperazin-1-yl-pyridine-2-carboxamide, 2HCl (intermediate33) (48.9 mg, 0.16 mmol) and7-(bromomethyl)-8-chloro-3-ethyl-1H-quinoxalin-2-one (intermediate 29)(48 mg, 0.16 mmol) in acetonitrile (10 mL) and the resulting mixture wasstirred at 70° C. for 2 h gave a suspension. LCMS indicated fullconversion. The mixture was cooled to rt, solid was collected byfiltration, washed with water and dried to yield5-[4-[(5-chloro-2-ethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 11) (42.0 mg, 58%) as a white solid. 1H NMR (500 MHz, DMSO-d6)1.22 (3H, t), 2.65 (4H, br s), 2.78-2.88 (5H, m), 2.95 (4H, br s), 3.38(3H, s, overlapped water peak), 3.76 (2H, s), 7.47 (2H, dd), 7.71 (1H,d), 7.79 (1H, d), 8.42 (1H, br d), 11.59-11.99 (1H, m); m/z (ES⁺)[M+H]⁺=455.

Intermediate 35:1-bromo-2,4-difluoro-3-nitro-benzene

A mixture of 1,3-difluoro-2-nitrobenzene (intermediate 34) (19.5 g,122.57 mmol) and NBS (26.2 g, 147.08 mmol) in sulfuric acid (150 mL) wasstirred at 80° C. for overnight. LCMS indicated full conversion. Themixture was cooled to rt and slowly poured onto ice. This mixture wasextracted with ethyl acetate (200 ml), the organic layer was washed withwater (50 ml×2), sat. NaHCO₃ solution (50 ml×2), brine, dried (anhydrousNa₂SO₄), filtered and concentrated. The residue was purified on silicagel column (eluted with 0 to 20% ethyl acetate in hexanes) to yield1-bromo-2,4-difluoro-3-nitro-benzene (intermediate 35) (26.8 g, 92%) asa light-yellow oil. 1H NMR (500 MHz, DMSO-d6) 7.42-7.73 (1H, m),8.06-8.26 (1H, m); m/z (ES⁺) [M+H]⁺=238.

Intermediate 36: methyl2-(4-bromo-3-fluoro-2-nitro-anilino)-3-hydroxy-butanoate

DIPEA (8.56 mL, 48.99 mmol) was added slowly to a stirred solution of1-bromo-2,4-difluoro-3-nitro-benzene (intermediate 35) (5.3 g, 22.27mmol) and methyl 2-amino-3-hydroxybutanoate, HCl (4.53 g, 26.72 mmol) in1,4-dioxane (50 mL) at r.t and the resulting mixture was stirred at 40°C. for 3 h. LCMS indicated some starting material remaining. To themixture was added 800 mgs of the DL-threonine methyl ester HCl salt andthe mixture was then continued to stir at 40° C. for overnight. Thesolvent was removed under reduced pressure and the residue was purifiedon silica gel column (eluted with 0 to 30% ethyl acetate in hexanes) toyield methyl 2-(4-bromo-3-fluoro-2-nitro-anilino)-3-hydroxy-butanoate(intermediate 36) (4.69 g, 60%) as a bright orange solid. (HNMRindicated it was a mixture of diastereomers). 1H NMR (500 MHz,CHLOROFORM-d) 1.30-1.44 (3H, m), 3.81 (3H, s), 4.00-4.22 (1H, m),4.22-4.48 (1H, m), 6.32-6.68 (1H, m), 7.40-7.66 (2H, m); m/z (ES⁺)[M+H]⁺=351, 353.

Intermediate 37: methyl2-(4-bromo-3-fluoro-2-nitro-anilino)-3-fluoro-butanoate

DAST (0.919 mL, 6.95 mmol) was added slowly over 10 min to a mixture ofmethyl 2-(4-bromo-3-fluoro-2-nitro-anilino)-3-hydroxy-butanoate(intermediate 36) (2.22 g, 6.32 mmol) in CH₂Cl₂ (40 mL) at 0° C., themixture was stirred at 0° C. for 20 min. LCMS and TLC showed startingmaterial remaining. To the mixture was added 0.4 ml of DAST and reactionwas stirred another 10 min. The mixture was quenched with sat. NaHCO₃solution and extracted with DCM. The organic layer was dried (anhydrousNa2SO₄), filtered and concentrated to yield a yellow oil. Resultingresidue was purified on silica gel column (eluted with 0 to 30% ethylacetate in hexanes) to yield peak 2 as methyl2-(4-bromo-3-fluoro-2-nitro-anilino)-3-fluoro-butanoate (1.110 g, 50%)(intermediate 37) as a yellow oil and peak 4 as starting material methyl2-((4-bromo-3-fluoro-2-nitrophenyl)amino)-3-hydroxybutanoate (0.300 g,13%) along with other byproduct. 1H NMR (500 MHz, CHLOROFORM-d)1.37-1.51 (3H, m), 2.80-2.93 (0.5H, m), 3.00 (0.5H, br d), 3.75 (1.5H,s), 3.85 (1.5H, s), 4.40-4.56 (0.5H, m), 5.01-5.23 (0.5H, m), 6.43-6.58(0.5H, m), 6.71-6.74 (0.5H, m), 7.38-7.69 (2H, m). m/z (ES⁺) [M+H]⁺=353.

Intermediate 38:7-bromo-8-fluoro-3-(1-fluoroethyl)-3,4-dihydro-1H-quinoxalin-2-one

To a mixture of methyl2-(4-bromo-3-fluoro-2-nitro-anilino)-3-fluoro-butanoate (intermediate37) (1.11 g, 3.14 mmol), Zinc (2.466 g, 37.72 mmol) and ammoniumchloride (3.36 g, 62.87 mmol) in MeOH (20 mL) was added water (2 mL) andthe mixture was stirred at rt for 10 min. The orange color disappeared(exothermic) and LCMS showed full conversion. The mixture was filtered,the solid washed with methanol and the filtrate was concentrated. Theresulting residue was dissolved DCM and the organic was washed withwater, dried (anhydrous Na2SO₄), filtered and concentrated to yieldcrude product. The residue was purified on silica gel column (0 to 30%ethyl acetate in hexanes) to yield methyl2-((2-amino-4-bromo-3-fluorophenyl)amino)-3-fluorobutanoate (0.533 g,52%) a light yellow solid.

Above yellow solid was dissolved in 15 ml of methanol, 0.5 1M HCl inmethanol was added and the reaction was stirred at rt for 4 h. LCMSindicated full conversion. The solvent was removed, and the residue wasdiluted with DCM/methanol (5:1). The organic layer was washed once with50% NaHCO₃ solution, dried (anhydrous Na2SO₄) and concentrated. Theresidue was purified on silica gel column (eluted with 0 to 31% ethylacetate in hexanes) to yield7-bromo-8-fluoro-3-(1-fluoroethyl)-3,4-dihydro-1H-quinoxalin-2-one(intermediate 38) (0.337 g, 37%) as a white solid. 1H NMR (500 MHz,METHANOL-d4) 1.27-1.46 (3H, m), 4.26 (1H, dd), 4.90-5.12 (1H, m), 6.50(1H, dd), 6.97 (1H, dd). m/z (ES⁺) [M+H]⁺=291, 293.

Intermediate 39: 7-bromo-8-fluoro-3-(1-fluoroethyl)-1H-quinoxalin-2-one

DDQ (289 mg, 1.27 mmol) was added to a slurry of7-bromo-8-fluoro-3-(1-fluoroethyl)-3,4-dihydro-1H-quinoxalin-2-one(intermediate 38) (337 mg, 1.16 mmol) in CH₂Cl₂ (10 mL) and the mixturewas stirred at rt for 2 h. The solvent was removed under reducedpressure, the residue was diluted with sat. NaHCO₃ solution (˜20 ml) andthe suspension was stirred at r.t for 3 h. The solid was collected byfiltration, washed with water and dried to yield7-bromo-8-fluoro-3-(1-fluoroethyl)-1H-quinoxalin-2-one (intermediate 39)(333 mg, 100%) as a white solid. 1H NMR (500 MHz, METHANOL-d4) 1.65-1.84(3H, m), 5.87-6.18 (1H, m), 7.50-7.60 (1H, m), 7.61-7.78 (1H, m). m/z(ES⁺) [M+H]⁺=289, 291.

Intermediate 40:8-fluoro-3-(1-fluoroethyl)-7-(hydroxymethyl)-1H-quinoxalin-2-one

A mixture of Pd-PEPPSI™-IPent catalyst (26 mg, 0.03 mmol),(tributylstannyl)methanol (1638 mg, 5.10 mmol) and7-bromo-8-fluoro-3-(1-fluoroethyl)-1H-quinoxalin-2-one (intermediate 39)(590 mg, 2.04 mmol) in 1,4-dioxane (25 mL) was degassed, back filledwith N2 and the mixture was stirred at 80° C. for 17 h. The mixture wasconcentrated, and the residue was purified on silica gel column (elutedwith 0 to 50% ethyl acetate in hexanes (to recover the remaining SM)followed by 0 to 20% methanol in DCM) to yield8-fluoro-3-(1-fluoroethyl)-7-(hydroxymethyl)-1H-quinoxalin-2-one(intermediate 40) (282 mg, 57%). 1H NMR (500 MHz, DMSO-d6) 1.58-1.81(3H, m), 4.67 (2H, br d), 5.46 (1H, br t), 5.87-6.24 (1H, m), 7.33-7.48(1H, m), 7.65 (1H, brd), 12.65-12.83 (1H, m); m/z (ES⁺) [M+H]⁺=241.

Intermediate 41:7-(bromomethyl)-8-fluoro-3-(1-fluoroethyl)-1H-quinoxalin-2-one

A suspension of triphenylphosphine (1223 mg, 4.66 mmol) and8-fluoro-3-(1-fluoroethyl)-7-(hydroxymethyl)-1H-quinoxalin-2-one (280mg, 1.17 mmol) (intermediate 40) in CH₂Cl₂ (15 mL) was cooled to 0° C.,carbon tetrabromide (1546 mg, 4.66 mmol) was added, the mixture turnedclear and purple color instantly, the mixture was continued to stir atthis temperature for 10 min, the mixture turned into a yellow solution,checked by LCMS which indicated full conversion (not very clean), themixture was concentrated, purified on silica gel column (eluted with 0to 20% methanol in DCM) to yield a major peak as7-(bromomethyl)-8-fluoro-3-(1-fluoroethyl)-1H-quinoxalin-2-one(intermediate 41) which was contaminated by some impurities.Concentrated to yield 2.5 g of solid (theory mass was 353 mgs, assumed100% yield to carry over to next step), m/z (ES⁺) [M+H]⁺=303, 305.

Example 12 and Example 13: 6-fluoro-5-[4-[[5-fluoro-2-[(1 S and1R)-1-fluoroethyl]-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

DIPEA (0.265 mL, 1.52 mmol) was added to a mixture of7-(bromomethyl)-8-fluoro-3-(1-fluoroethyl)-1H-quinoxalin-2-one(intermediate 41) (115 mg, 0.38 mmol) and6-fluoro-N-methyl-5-(piperazin-1-yl)picolinamide, 2HCl (94 mg, 0.30mmol) (intermediate 32) in acetonitrile (20 mL) and the resultingmixture was stirred at 70° C. for 1 h. LCMS indicated full conversion.The mixture was concentrated, the residue was dissolved in DMSO (˜4 ml)and purified on C18 reverse phase column (eluted with 0 to 100%ACN/water/0.1% TFA). The product containing fractions were combined andlyophilized to dryness. Material was repurified on Gilson (eluted with 0to 80% ACN/water/0.1% TFA) to yield the product6-fluoro-5-[4-[[5-fluoro-2-[(1S and1R)-1-fluoroethyl]-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide.The enantiomers were separated by chiral column. Chiral purificationconditions: Column info: chiralpak OD 4.6 mm×100 mm 5 μm, mobile phaseA: CO₂ (100%), mobile phase B: methanol with 0.2% NH₄OH, isocratic 25% Bover 6 min, flow rate: 4.0 ml/min, diluent: methanol, columntemperature: room temperature, Outlet pressure (SFC): N/A.

Peak 1:

The white solid was diluted with water and ACN 0.1 mL of aq. 0.5M HClwas added and the mixture was lyophilized to dryness to yield isomer1,6-fluoro-5-[4-[[5-fluoro-2-[(1S OR1R)-1-fluoroethyl]-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideas a HCl salt (Example 12, absolute stereochemistry not determined)(5.42 mg, 10.90 μmol, 3%) as HCl salt as a yellow solid. 1H NMR (500MHz, DMSO-d6) 1.54-1.73 (3H, m), 2.70-2.87 (3H, m), 3.53-3.90 (8H, m),4.57 (2H, brs), 5.79-6.21 (1H, m), 7.59-7.81 (3H, m), 7.87 (1H, d), 8.43(1H, br d), 11.40-11.85 (1H, m), 12.78-13.14 (1H, m); m/z (ES⁺)[M+H]⁺=461, >95% ee.

Peak 2:

The white solid was diluted with water and ACN, 0.1 mL of aq. 0.5M HClwas added and the mixture was lyophilized to dryness to yield isomer 2,6-fluoro-5-[4-[[5-fluoro-2-[(1S OR1R)-1-fluoroethyl]-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideas a HCl salt (Example 13, absolute stereochemistry not determined). 1HNMR (500 MHz, DMSO-d6) 1.49-1.83 (3H, m), 2.77 (3H, br d), 3.46-3.91(8H, m), 4.56 (2H, br s), 5.80-6.26 (1H, m), 7.52-7.80 (3H, m), 7.87(1H, br d), 8.43 (1H, br d), 11.44-11.82 (1H, m), 12.77-13.24 (1H, m);m/z (ES⁺) [M+H]⁺=461, >95% ee.

Example 14 and Example 15: 5-[4-[[5-fluoro-2-[(1S and1R)-1-fluoroethyl]-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

To a suspension of7-(bromomethyl)-8-fluoro-3-(1-fluoroethyl)quinoxalin-2(1H)-one(intermediate 41) (138 mg, 0.41 mmol) andN,6-dimethyl-5-(piperazin-1-yl)picolinamide, 2HCl (126 mg, 0.41 mmol)(intermediate 33) in acetonitrile (13 mL) was added DIPEA (429 μl, 2.46mmol) and the resulting mixture was stirred at 70° C. for 3 h. LCMSindicated full conversion. Reaction was concentrated and the residue waspurified on silica gel column (eluted with 0 to 20% methanol in DCM) toyield the racemic product5-[4-[[5-fluoro-2-[(1S/1R)-1-fluoroethyl]-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamideas a light yellow solid (169 mgs). Enantiomers were separated by chiralseparation. Chiral purification conditions: Column info: chiralpak OD21.2 mm×250 mm 5 μm, mobile phase A: CO₂ (100%), mobile phase B:methanol with 0.2% NH₄OH, isocratic: 25% B over 12 min, flow rate: 70.0ml/min, concentration: 8.45 mg/ml in methanol, loading: 4.23mg/injection, column temperature: room temperature, Outlet pressure(SFC): N/A.

After chiral separation, each isomer was repurified on reverse phasecolumn (eluted with 0 to 60% ACN/water/0.2% ammonium hydroxide) toyield;

Peak 1:

5-[4-[[5-fluoro-2-[(1S OR1R)-1-fluoroethyl]-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide,isomer 1 (example 14, absolute stereochemistry not determined) (30.7 mg,0.067 mmol, 16%) as a white solid. 1H NMR (500 MHz, DMSO-d6) 1.40-1.70(3H, m), 2.48 (3H, s), 2.54-2.69 (4H, m), 2.79 (3H, d), 2.94 (4H, brs),3.74 (2H, s), 5.83-6.22 (1H, m), 7.17-7.41 (1H, m), 7.47 (1H, d), 7.65(1H, d), 7.78 (1H, d), 8.40 (1H, brd), 11.65-12.88 (1H, m); m/z (ES⁺)[M+H]⁺=457; >98% ee.

Peak 2:

5-[4-[[5-fluoro-2-[(1S OR1R)-1-fluoroethyl]-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide,isomer 2 (example 15, absolute stereochemistry not determined) (37 mg,0.081 mmol, 20%) as a white solid. 1H NMR (500 MHz, CHLOROFORM-d)1.68-1.88 (3H, m), 2.51 (3H, s), 2.71 (4H, br s), 2.86-3.12 (7H, m),3.81 (2H, s), 5.92-6.29 (1H, m), 7.34 (1H, d), 7.44 (1H, t), 7.76 (1H,d), 7.95 (1H, br d), 7.99 (1H, d), 10.24 (1H, br s); m/z (ES⁺)[M+H]⁺=457; 94.5% ee.

Intermediate 43: methyl 2-(4-bromo-3-chloro-2-nitro-anilino)propanoate

A flask was charged with methyl alaninate, HCl (intermediate 42) (1.851g, 13.26 mmol) and 1-bromo-2-chloro-4-fluoro-3-nitrobenzene(intermediate 22) (2.25 g, 8.84 mmol) in 1,4-dioxane (70 mL). DIPEA(9.27 mL, 53.06 mmol) was added and the mixture was stirred at 105° C.for 24 h gave a brown solution. LCMS showed reaction was complete. Themixture was concentrated, and the residue was purified on silica gelcolumn (eluted with 0 to 30% ethyl acetate in hexanes) to yield methyl2-(4-bromo-3-chloro-2-nitro-anilino)propanoate (intermediate 43) (2.120g, 71%) as a bright yellow oil, turned into yellow solid after standing.1H NMR (500 MHz, CHLOROFORM-d) 1.52 (3H, d), 3.77 (3H, s), 6.53 (1H, d),7.15 (1H, t), 7.53 (1H, d), 7.78 (1H, dd); m/z (ES⁺) [M+H]⁺=337.

Intermediate 44:7-bromo-8-chloro-3-methyl-3,4-dihydro-1H-quinoxalin-2-one

Sodium dithionite (3.28 g, 18.84 mmol) was added to a stirred solutionof methyl 2-(4-bromo-3-chloro-2-nitro-anilino)propanoate (intermediate43) (2.12 g, 6.28 mmol) in DMSO (50 mL) and the mixture was stirred at120° C. for 5 h. LCMS and TLC indicated full conversion. The mixture wasquenched with water and extracted with ethyl acetate (50 ml×2). Theorganic layer was dried (anhydrous Na₂SO₄), filtered, concentrated andthe residue was purified on silica gel column (0 to 55% ethyl acetate inhexanes) to yield 7-bromo-8-chloro-3-methyl-1H-quinoxalin-2-one(intermediate 45) (0.055 g, 3%). m/z (ES+) [M+H]+ 273, 275 and7-bromo-8-chloro-3-methyl-3,4-dihydro-1H-quinoxalin-2-one (intermediate44) (0.190 g, 11%). m/z (ES⁺) [M+H]⁺=275, 277.

Intermediate 45: 7-bromo-8-chloro-3-methyl-1H-quinoxalin-2-one

DDQ (157 mg, 0.69 mmol) was added to a mixture of7-bromo-8-chloro-3-methyl-3,4-dihydro-1H-quinoxalin-2-one (intermediate44) (190 mg, 0.69 mmol) in 1,4-dioxane (10 mL) and the resulting mixturewas stirred at rt for overnight, LCMS indicated full conversion. Themixture was concentrated and the residue was treated with sat. NaHCO₃solution. Mixture was stirred at rt for 4, solid was isolated byfiltration, washed with sat. NaHCO₃ solution and water. The solid wasthen purified on silica gel column (eluted with 0 to 20% methanol inDCM) to yield 7-bromo-8-chloro-3-methyl-1H-quinoxalin-2-one(intermediate 45) (122 mg, 65%) as a yellow solid, m/z (ES⁺) [M+H]⁺=273,275.

Intermediate 46: 8-chloro-3-methyl-7-vinyl-1H-quinoxalin-2-one

A mixture of 7-bromo-8-chloro-3-methyl-1H-quinoxalin-2-one (intermediate45) (122 mg, 0.45 mmol), tetrakis(triphenylphosphine)palladium(0) (51.5mgs, 0.04 mmol) and tributyl(vinyl)stannane (212 mg, 0.67 mmol) intoluene (15 ml) was stirred at 110° C. under N₂ for 16 h. LCMS indicatedreaction completion. The mixture was concentrated, and residue waspurified on silica gel column (eluted with 0 to 16% methanol in DCM) toyield 8-chloro-3-methyl-7-vinyl-1H-quinoxalin-2-one (intermediate 46)(98 mg, 100%) as a brown solid, (contaminated by PPh₃O). m/z (ES⁺)[M+H]⁺=221.

Intermediate 47: 5-chloro-2-methyl-3-oxo-4H-quinoxaline-6-carbaldehyde

Osmium tetroxide in H₂O (0.1 mL, 0.01 mmol) was added to a solution of8-chloro-3-methyl-7-vinyl-1H-quinoxalin-2-one (140 mg, 0.63 mmol)(intermediate 46), 2,6-lutidine (0.148 ml, 1.27 mmol) and sodiumperiodate (543 mg, 2.54 mmol) in THF (10 mL)/water (2 mL)/tert-butanol(0.607 mL, 6.34 mmol) and stirred at rt for overnight gave a yellowsuspension. LCMS and TLC indicated there was still starting materialremained. To the mixture was added THF (10 ml)/water (2.000 ml), 200 mgsof sodium periodate, 0.3 ml of osmium tetroxide and the mixture wascontinued to stir at rt for 5 h. LCMS indicated full conversion.Reaction was diluted with water, sat. NH₄Cl solution was added andextracted with DCM. The combined organic layer was dried (anhydrousNa₂SO₄), filtered and concentrated. The residue was purified on silicagel column (eluted with 0 to 20% methanol in DCM) to yield5-chloro-2-methyl-3-oxo-4H-quinoxaline-6-carbaldehyde (intermediate 47)(141 mg, 100%) as a yellow solid, (not very pure, carried over to thenext step), m/z (ES⁺) [M+H]⁺=223.

Intermediate 48: 8-chloro-7-(hydroxymethyl)-3-methyl-1H-quinoxalin-2-one

Sodium borohydride (23.96 mg, 0.63 mmol) was added to a cooled solutionof 5-chloro-2-methyl-3-oxo-4H-quinoxaline-6-carbaldehyde (intermediate47) (141 mg, 0.63 mmol) in a mixture of MeOH (16 mL) and DCM (8.00 mL)was cooled to 0° C. and the mixture was continued to stir at 0° C. for 1h. LCMS indicated full conversion. To the mixture was added 1 ml ofwater, concentrated and the residue was purified on silica gel column(eluted with 40 to 100% ethyl acetate in hexanes; then 0 to 20% methanolin DCM) to yield 8-chloro-7-(hydroxymethyl)-3-methyl-1H-quinoxalin-2-one(intermediate 48) (142 mg, 100%) as a yellow solid; 1H NMR (500 MHz,DMSO-d6) 2.42 (3H, s), 4.65 (2H, brd), 5.53 (1H, br t), 7.46 (1H, brd),7.69 (1H, br d), 11.77 (1H, br s); m/z (ES⁺) [M+H]⁺=225.

Intermediate 49: 7-(bromomethyl)-8-chloro-3-methyl-1H-quinoxalin-2-one

8-chloro-7-(hydroxymethyl)-3-methyl-1H-quinoxalin-2-one (intermediate48) (142 mg, 0.63 mmol) and triphenylphosphine (332 mg, 1.26 mmol) inCH₂Cl₂ (20 ml) was cooled to 0° C. Perbromomethane (419 mg, 1.26 mmol)was added in one portion and the mixture was stirred at 0° C. for 1 hand at rt for 2 h. LCMS indicated no progress. To the mixture was addeda second portion of triphenylphosphine (332 mg, 1.26 mmol) andperbromomethane (419 mg, 1.26 mmol) at rt and the mixture was stirredfor 1 h. LCMS indicated full conversion. The solvent was removed underreduced pressure and the residue was purified on silica gel column(eluted with 0 to 100% ethyl acetate in hexanes) to yield the product7-(bromomethyl)-8-chloro-3-methyl-1H-quinoxalin-2-one as a yellow solid(intermediate 49) (32 mgs, 18%). Further elution with 20% methanol inDCM gave the second portion 100 mgs (55%) of the product as a brownsolid (47% purity), m/z (ES⁺) [M+H]⁺=287, 289.

Example 16:5-[4-[(5-chloro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

DIPEA (0.053 mL, 0.31 mmol) was added to a mixture ofN-methyl-5-(piperazin-1-yl)picolinamide, 2HCl (22.43 mg, 0.08 mmol)(intermediate 31) and7-(bromomethyl)-8-chloro-3-methyl-1H-quinoxalin-2-one (intermediate 49)(22 mg, 0.08 mmol) in acetonitrile (4 mL) and the resulting suspensionwas stirred at 70° C. for 1 h. LCMS indicated full conversion. Themixture was concentrated, the residue was dissolved in DMSO and purifiedon reverse phase C18 column (eluted with 0 to 100% ACN/water/0.1% TFA).The fractions containing pure product were lyophilized to dryness toyield5-[4-[(5-chloro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(20 mg, 56%). 1 mL of 2M HCl in ether was added and the solvent wasremoved under vacuum to give the corresponding HCl salt as a yellowsolid (example 16). 1H NMR (500 MHz, METHANOL-d4) 2.96-3.03 (3H, m),3.48-3.86 (6H, m), 4.04-4.41 (2H, m), 4.78 (2H, s), 4.86 (3H, d, mergedinto water peak), 7.74 (1H, d), 7.84 (1H, d), 8.14 (1H, dd), 8.31 (1H,d), 8.47 (1H, d); m/z (ES⁺) [M+H]⁺=427.

Example 17:5-[4-[(5-chloro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide

DIPEA (0.061 mL, 0.35 mmol) was added to a mixture of6-fluoro-N-methyl-5-(piperazin-1-yl)picolinamide, 2HCl (intermediate 32)(27.1 mg, 0.09 mmol) and7-(bromomethyl)-8-chloro-3-methyl-1H-quinoxalin-2-one (intermediate 49)(50 mg, 0.09 mmol) (around 50% purity) in acetonitrile (5 mL) and theresulting solution was stirred at 70° C. for 1 h. LCMS indicated fullconversion. The mixture was concentrated, and the residue was dissolvedin DMSO and purified on a reverse phase C18 column (eluted with 0 to100% ACN/water/0.1% TFA), then purified a second time on a reverse phaseC18 column (eluted with 0 to 100% ACN/water/0.1% TFA). Material wasfinally purified a third time on reverse phase column (eluted with 0 to100% ACN/water/ammonium hydroxide, PH˜10) to yield5-[4-[(5-chloro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide(example 17) (16.50 mg, 43%) as a white solid. 1H NMR (500 MHz, DMSO-d6)2.37-2.47 (3H, m), 2.63 (4H, br s), 2.76 (3H, d), 3.13-3.23 (4H, m),3.74 (2H, s), 7.45 (1H, d), 7.57 (1H, dd), 7.68 (1H, d), 7.84 (1H, d),8.39 (1H, brd), 10.71-12.11 (1H, m); m/z (ES⁺) [M+H]⁺=445.

Example 18:5-[4-[(5-chloro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

DIPEA (0.061 mL, 0.35 mmol) was added to a mixture ofN,6-dimethyl-5-(piperazin-1-yl)picolinamide, 2HCl (intermediate 33)(26.7 mg, 0.09 mmol) and7-(bromomethyl)-8-chloro-3-methyl-1H-quinoxalin-2-one (50 mg, 0.09 mmol)(intermediate 49, ˜50% purity) in acetonitrile (5 mL) and the resultingsolution was stirred at 70° C. for 1 hr. LCMS indicated full conversion.The mixture was concentrated, the residue was dissolved in DMSO and theresidue was purified on reverse phase C18 column (eluted with 0 to 100%ACN/water/0.1% TFA). After concentration of the fraction, the residuewas repurified on reverse phase C18 column (eluted with 0 to 100%ACN/water/ammonium hydroxide, PH˜10). The pure fractions werelyophilized to dryness to yield5-[4-[(5-chloro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 18) (18.4 mg, 48%) as free base. 1H NMR (500 MHz, METHANOL-d4)2.53 (6H, d), 2.76 (4H, brs), 2.94 (3H, s), 3.04 (4H, br t), 3.86 (2H,s), 7.48 (1H, d), 7.51-7.60 (1H, m), 7.69 (1H, d), 7.86 (1H, d); m/z(ES⁺) [M+H]⁺=441.

Intermediate 50:7-bromo-8-fluoro-3-(1-hydroxyethyl)-3,4-dihydro-1H-quinoxalin-2-one

Ammonium chloride (6.70 g, 125.31 mmol) was added to a suspension ofmethyl 2-((4-bromo-3-fluoro-2-nitrophenyl)amino)-3-hydroxybutanoate(intermediate 36) (4.4 g, 12.53 mmol) and zinc (8.19 g, 125.31 mmol) inMeOH (65 mL) at 0° C. To this was added water (2 mL) and the mixture wasstirred at 0° C. for 60 min. The orange color disappeared whichindicated full conversion, LCMS indicated the reaction was complete. Themixture was filtered, washed with methanol and the filtrate wasconcentrated. The residue was diluted with ethyl acetate/methanol(10/1), the organic was washed e with water (˜20 ml), brine, dried(anhydrous Na2SO₄), concentrated to yield the intermediate methyl2-((2-amino-4-bromo-3-fluorophenyl)amino)-3-hydroxybutanoate.

The above solid was slurried in methanol (˜30 ml), 4 M HCl in dioxanes(˜1 ml) was added and the mixture was stirred at rt for 2 h. LCMSindicated full conversion. The mixture was concentrated, and the residuewas purified on silica gel column (eluted with 0 to 100% ethyl acetatein hexanes) to yield7-bromo-8-fluoro-3-(1-hydroxyethyl)-3,4-dihydro-1H-quinoxalin-2-one(intermediate 50) (3.20 g, 88%) as a yellow solid, (a mixture ofdiastereomers). m/z (ES⁺) [M+H]⁺=289, 291.

Intermediate 51: 7-bromo-8-fluoro-3-(1-hydroxyethyl)-1H-quinoxalin-2-one

DDQ (432 mg, 1.90 mmol) was added to a suspension of7-bromo-8-fluoro-3-(1-hydroxyethyl)-3,4-dihydro-1H-quinoxalin-2-one(intermediate 50) (500 mg, 1.73 mmol) in CH₂Cl₂ (30 mL) and the mixturewas stirred at rt for overnight. LCMS indicated clean conversion. Thesolvent was removed under reduced pressure, sat. NaHCO₃ (˜100 ml)solution was added and the mixture was stirred at rt for 3 h. The solidwas collected by filtration, washed with water and dried to yield7-bromo-8-fluoro-3-(1-hydroxyethyl)-1H-quinoxalin-2-one (intermediate51) (439 mg, 88%). 1H NMR (500 MHz, DMSO-d6) 1.39 (3H, d), 4.78-5.31(2H, m), 7.39-7.71 (2H, m), 12.72 (1H, brs); m/z (ES⁺) [M+H]⁺=287, 289.

Intermediate 52: 3-acetyl-7-bromo-8-fluoro-1H-quinoxalin-2-one

A solution of DMSO (0.651 mL, 9.17 mmol) in DCM was added dropwise to astirred solution of oxalyl chloride (3.06 mL, 6.12 mmol) (2 M in DCM) indichloromethane (20 ml) at −78° C. The solution of7-bromo-8-fluoro-3-(1-hydroxyethyl)-1H-quinoxalin-2-one (intermediate51) (439 mg, 1.53 mmol) was added slowly to the above reaction mixtureand the resultant slurry was stirred for 15 min at −78° C. Triethylamine(1.279 mL, 9.17 mmol) was added dropwise and the resultant slurry wasstirred an additional 30 min at 0° C. LCMS indicated the formation ofdesired product. Water (30 ml) was added and the mixture was extractedwith dichloromethane/MeOH (5:1) (2×50 ml). The organic phases werecombined and dried over magnesium sulfate. The solvent was removed undervacuum and the residue was purified by reverse phase C18 column (elutedwith 0 to 100% ACN/water/0.1% TFA) to yield3-acetyl-7-bromo-8-fluoro-1H-quinoxalin-2-one (intermediate 52) (85 mg,19%) as a yellow solid. 1H NMR (500 MHz, DMSO-d6) 2.52-2.66 (3H, m),7.42-7.76 (2H, m), 13.03 (1H, br s). m/z (ES⁺) [M+H]⁺=285, 287.

Intermediate 53: 7-bromo-3-d,1-difluoroethyl)-8-fluoro-1H-quinoxalin-2-one

DAST (0.148 mL, 1.12 mmol) was added to a suspension of3-acetyl-7-bromo-8-fluoro-1H-quinoxalin-2-one (intermediate 52) (80 mg,0.28 mmol) in CH₂Cl₂ (20 mL) at rt and the resulting suspension wasstirred at rt for 24 h. LCMS indicated 42% of the product formation. Themixture was continued to stir for over the weekend. To the mixture wasadded water and extracted with DCM. The organic layer was dried(anhydrous Na2SO₄), filtered and concentrated. The residue was purifiedon silica gel column (eluted with 0 to 20% methanol in DCM) to yield7-bromo-3-(1,1-difluoroethyl)-8-fluoro-1H-quinoxalin-2-one (intermediate53) (65.0 mg, 75%) as a light yellow solid, m/z (ES⁺) [M+H]⁺=307, 309.(the material was not very pure, carried onto next step).

Intermediate 54: 3-d,1-difluoroethyl)-8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one

A mixture of (tributylstannyl)methanol (102 mg, 0.32 mmol), Xphos Pd G2(24.98 mg, 0.03 mmol) and7-bromo-3-(1,1-difluoroethyl)-8-fluoro-1H-quinoxalin-2-one (intermediate53) (65 mg, 0.21 mmol) in 1,4-dioxane (10 mL) was stirred at 80° C. for6 h under N2 atmosphere. LCMS indicated full conversion. Solvent wasremoved under vacuum and the residue was purified on silica gel column(eluted with 0 to 20% methanol in DCM) to yield3-(1,1-difluoroethyl)-8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one(intermediate 54) (55.0 mg, 100%) as a brown solid, m/z (ES⁺)[M+H]⁺=259.

Intermediate 55:7-(bromomethyl)-3-(1,1-difluoroethyl)-8-fluoro-1H-quinoxalin-2-one

CBr₄ (129 mg, 0.39 mmol) was added to a mixture of3-(1,1-difluoroethyl)-8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one(intermediate 54) (67 mg, 0.26 mmol) and triphenylphosphine (102 mg,0.39 mmol) in CH₂Cl₂ (6 mL) at 0° C. and the resulting mixture wasstirred at rt for overnight. LCMS indicated full conversion. The solventwas removed under vacuum and the residue was purified on silica gelcolumn (eluted with 0 to 100% ethyl acetate in hexanes) to yield7-(bromomethyl)-3-(1,1-difluoroethyl)-8-fluoro-1H-quinoxalin-2-one(intermediate 55) (56.0 mg, 67%) as a white solid, m/z (ES⁺) [M+H]⁺=321,323.

Example 19:5-[4-[[2-(1,1-difluoroethyl)-5-fluoro-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

To a suspension of7-(bromomethyl)-3-(1,1-difluoroethyl)-8-fluoro-1H-quinoxalin-2-one(intermediate 55) (56 mg, 0.16 mmol) andN,6-dimethyl-5-(piperazin-1-yl)picolinamide, 2HCl (intermediate 33)(48.2 mg, 0.16 mmol) in acetonitrile (4 mL) was added DIPEA (0.164 mL,0.94 mmol) and the resulting mixture was stirred at 70° C. for 1.5 h.LCMS indicated full conversion. The mixture was concentrated, and theresidue was purified on reverse phase Gilson column (eluted with 0 to70% ACN/water/0.1% TFA). The pure fractions were combined, 0.5 ml of aq.1M HCl was added to the combined fractions and lyophilized to dryness toyield5-[4-[[2-(1,1-difluoroethyl)-5-fluoro-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamideas HCl salt (example 19) (35.0 mg, 44%) as a yellow solid. 1H NMR (500MHz, DMSO-d6) 2.08 (3H, br t), 2.52 (3H, s), 2.80 (3H, br d), 3.02-3.54(8H, m), 4.61 (2H, br s), 7.57 (1H, br d), 7.67-8.04 (3H, m), 8.52 (1H,br d), 11.74 (1H, br s), 12.77-13.55 (1H, m); m/z (ES⁺) [M+H]⁺=475.

Intermediate 56: methyl 2-(4-bromo-3-fluoro-2-nitro-anilino)propanoate

DIPEA (151 ml, 867.27 mmol) was added slowly to a stirred solution of1-bromo-2,4-difluoro-3-nitrobenzene (intermediate 35) (68.8 g, 289.09mmol) and methyl alaninate, HCl (40.4 g, 289.09 mmol) in DMF (300 mL).The resulting solution was stirred at rt for 18 hours (Completeconversion to desired product by LCMS). Reaction mixture wasconcentrated using rocket evaporation system, diluted with water andextracted with ethyl acetate. Organic layer was washed thoroughly withwater, dried over sodium sulphate, filtered and concentrated undervacuum. 100 mL DCM was added to the above orange solid, the suspensionwas stirred at r.t for 30 min, and the solid was filtered to yieldmethyl 2-(4-bromo-3-fluoro-2-nitro-anilino)propanoate (24.00 g, 26%)(intermediate 56) as a bright orange solid. 1H NMR (500 MHz,DICHLOROMETHANE-d2) 1.52-1.62 (3H, m), 3.80 (3H, s), 4.28 (1H, quin),6.49 (1H, dd), 7.19-7.39 (1H, m), 7.54 (1H, dd); 19F NMR (471 MHz,DICHLOROMETHANE-d2) −109.49 (1F, s); m/z (ES⁺) [M+H]⁺=321, 323.

Intermediate 57:7-bromo-8-fluoro-3-methyl-3,4-dihydro-1H-quinoxalin-2-one

Zinc (78 g, 1195.88 mmol) was added portion wise to a mixture of methyl2-(4-bromo-3-fluoro-2-nitro-anilino)propanoate (intermediate 56) (48 g,149.49 mmol) and ammonium chloride (64.0 g, 1195.88 mmol) in MeOH (720ml) and water (16 ml) at 0° C. (exothermic reaction) and the mixture wasstirred at rt for 2 h (Complete disappearance of orange coloration isindicative of reaction completion). Solid was filtered off and the solidcake was washed with 20% MeOH in DCM. The filtrate was concentrated,water was added to the crude product and the product was extracted byethyl acetate. The organic layer was dried and concentrated under vacuumto furnish an oil. m/z (ES⁺) [M+H]⁺=291, 293.

This material was slurry in ethyl acetate (50 mL) and methanol (50 mL),2 mL 4N HCl in dioxane was added and the mixture was stirred for 1 h.The reaction mixture was concentrated to yield the crude product7-bromo-8-fluoro-3-methyl-3,4-dihydro-1H-quinoxalin-2-one (intermediate57) (38.7 g) as a grey solid. The crude product (38.7 g) was subjectedto the next step without any further purification assuming the yield ofthis reaction to be 100%. m/z (ES⁺) [M+H]⁺=259.

Intermediate 58: 7-bromo-8-fluoro-3-methyl-1H-quinoxalin-2-one

DDQ (21.55 g, 94.95 mmol) was added in one portion to a stirred solutionof 7-bromo-8-fluoro-3-methyl-3,4-dihydro-1H-quinoxalin-2-one(intermediate 57) (20.5 g, 79.13 mmol) in DCM (200 mL), resulted in avery thick off-white slurry, added additional dichloromethane (800 mL).The resulting slurry was stirred at rt for 2 hours (Complete conversionto desired product by LCMS). The reaction mixture was concentrated undervacuum and quenched with saturated aq. sodium bicarbonate solution(about 500 mL, quenching leads to intense frothing). The above slurrywas stirred at rt for overnight and the solid was filtered off, washedthoroughly with water and solid dried on the filter for overnight. Thissolid was washed with diethyl ether and dried for 30 mins to give7-bromo-8-fluoro-3-methyl-1H-quinoxalin-2-one (intermediate 58) (16.28g, 80%) as an off-white solid. 19F NMR (471 MHz, DMSO-d6) −124.18 (1F,s); 1H NMR (500 MHz, DMSO-d6) 2.41 (3H, s), 7.45-7.54 (2H, m), 12.60(1H, brs); m/z (ES⁺) [M+H]⁺=257.

Intermediate 17: 8-fluoro-7-(hydroxymethyl)-3-methyl-1H-quinoxalin-2-one

A mixture of (tributylstannyl)methanol (15.39 g, 47.93 mmol),7-bromo-8-fluoro-3-methyl-1H-quinoxalin-2-one (intermediate 58) (11.2 g,43.57 mmol) and Xphos Pd G2 (1.714 g, 2.18 mmol) in 1,4-dioxane (200 mL)was stirred at 80° C. for 7 h. LCMS indicated full conversion. Thesolvent was removed under reduced pressure, the residue was purified onsilica gel column (eluted with 0 to 15% methanol in DCM). The fractionswere concentrated to a slurry, diluted with ether, the solid wascollected by filtration and dried to yield8-fluoro-7-(hydroxymethyl)-3-methyl-1H-quinoxalin-2-one (intermediate17) (8.10 g, 89%) as a white solid. 1H NMR (500 MHz, DMSO-d6) 2.41 (3H,s), 4.63 (2H, br d), 5.39 (1H, t), 7.31 (1H, br t), 7.51 (1H, d), 12.41(1H, brs). m/z (ES⁺) [M+H]⁺=209.

Example 20:6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

Triethylphosphane (20.90 ml, 145.06 mmol) was added dropwise with anaddition funnel to a stirred suspension of8-fluoro-7-(hydroxymethyl)-3-methyl-1H-quinoxalin-2-one (intermediate17) (15.1 g, 72.53 mmol) and 1,2-dibromo-1,1,2,2-tetrachloroethane (52.0g, 159.56 mmol) in DCM (400 mL) at 0° C. under nitrogen. The mixture wasstirred at r.t for 3 h gave a light-yellow suspension. Crude LCMSindicated full conversion. DCM was removed under vacuum; the residue wasslurry in 300 mL diethyl ether at rt and the light yellow ppt wasfiltered and washed with 200 ml ether. The solid was taken into 300 mlof water, stirred at rt for 10 min, the solid was collected byfiltration, thorough wash (200 ml) with water to remove the salts. Thesolid was dried under vacuum for overnight (no heat). The solid waswashed with hexanes and dried in vacuum in a bushel funnel to give7-(bromomethyl)-8-fluoro-3-methylquinoxalin-2(1H)-one (intermediate 59)(22.76 g, 116%, likely contains some inorganic salts) as an off whitesolid. Used as such for next reaction. 1H NMR (500 MHz, DMSO-d6) 2.42(3H, s), 4.65-4.93 (2H, m), 7.28-7.42 (1H, m), 7.51 (1H, d), 12.53 (1H,br s); m/z (ES⁺) [M+H]⁺=271, 273.

To a flask charged with7-(bromomethyl)-8-fluoro-3-methylquinoxalin-2(1H)-one (intermediate 59)(22.76 g) and 6-fluoro-N-methyl-5-(piperazin-1-yl)picolinamide, 2HCl(intermediate 32) (24.24 g, 77.9 mmol) in acetonitrile (350 ml), wasadded DIPEA (38.0 ml, 217.59 mmol) at rt and the resulting mixture wasstirred at 70° C. for 4 h. Reaction was not complete. To the mixture wasadded 5 g of KI and 2 g of NaI and the mixture was stirred at 50° C. for20 h. More 540 mgs (˜0.03 eq) of6-fluoro-N-methyl-5-(piperazin-1-yl)picolinamide, 2HCl (intermediate 32)was added to the mixture and the stirring continued at 50° C. for 2 h.The solid from the reaction suspension was collected by filtration,washed with acetonitrile and dried. The resulting material was thensuspended in water (˜400 ml), slurred at rt for 20 min, filtered anddried (97% purity by LCMS). The solid was then dissolved into a mixtureof DCM/MeOH (3/1) (about 1.5 L) at reflux, filtered through a pad ofsilica gel, removed most of the DCM until solid precipitate out and themixture was kept at rt for 20 min. The solid was collected by filtrationand repeated the procedure for the filtrate, and the solids werecombined to yield the product6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 20) (26 g, 84%) as a light yellow solid. 1H NMR (500 MHz,DMSO-d6) 2.41 (3H, s), 2.57-2.69 (4H, m), 2.76 (3H, d), 3.16 (4H, brs),3.70 (2H, s), 7.29 (1H, br t), 7.40-7.60 (2H, m), 7.83 (1H, d), 8.38(1H, brd), 12.44 (1H, brs); m/z (ES⁺) [M+H]⁺=429.

Example 21:6-(difluoromethyl)-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

DIPEA (0.052 mL, 0.30 mmol) was added to a stirred mixture of7-(bromomethyl)-8-fluoro-3-methylquinoxalin-2(1H)-one (intermediate 59)(40 mg, 0.15 mmol) and6-(difluoromethyl)-N-methyl-5-(piperazin-1-yl)picolinamide, 2HCl(intermediate 60) (50.6 mg, 0.15 mmol) in acetonitrile (mL) and Theresulting mixture was stirred at 70° C. for 2 h. Reaction wasconcentrated and submitted to analytical group for purification(Purification conditions: the residue was purified by reverse phase C18column (eluted with 0 to 100% ACN/water/0.1% NH₄OH) which yield6-(difluoromethyl)-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 21) (15 mg, 22%) as white solid. 1H NMR (500 MHz, DMSO-d6) 2.37(3H, s), 2.64 (4H, brs), 2.84 (3H, d), 3.01 (4H, brd), 3.70 (2H, s),7.00-7.28 (2H, m), 7.42 (1H, brd), 7.86 (1H, d), 8.09 (1H, d), 8.39 (1H,q), 12.24-12.63 (1H, m); m/z (ES⁺) [M+H]⁺=461.

Intermediate 61: methyl6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxylate

Polymer supported triphenylphosphine (1.512 g, 5.76 mmol) (3.4 g added,calculated based on PPh₃ loading of 1.6 mmol/g) was added to a stirredslurry of 8-fluoro-7-(hydroxymethyl)-3-methylquinoxalin-2(1H)-one(intermediate 17) (400 mg, 1.92 mmol) and perbromomethane (1.274 g, 3.84mmol) in DCM (40 mL) at rt. The resulting mixture was stirred at 23° C.for 1 h. Reaction was not complete. Additional polymer bound-PPh₃ (1 g)was added to get the reaction to complete. Reaction mixture wasfiltered, washed with DCM, THF and the filtrate was concentrated undervacuum to yield 7-(bromomethyl)-8-fluoro-3-methylquinoxalin-2(1H)-one asa light-yellow solid.

To the above freshly prepared7-(bromomethyl)-8-fluoro-3-methylquinoxalin-2(1H)-one, was added methyl6-fluoro-5-(piperazin-1-yl)picolinate, 2HCl (intermediate 12) (600 mg,1.92 mmol), acetonitrile (25 mL) and N-ethyl-N-isopropylpropan-2-amine(1674 μl, 9.61 mmol) and the reaction mixture was heated to 70° C. 1 h.The reaction mixture was cooled to rt, concentrated, and the crude solidwas purified via normal phase chromatography using 0-10% MeOH in DCM toyield methyl6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxylate(intermediate 61) (0.484 g, 59%) as an off-white solid. 1H NMR (500 MHz,DMSO-d6) 2.34-2.49 (3H, m), 2.52-2.62 (4H, m), 3.08-3.28 (4H, m), 3.70(2H, s), 3.83 (3H, s), 7.29 (1H, t), 7.44-7.54 (2H, m), 7.91 (1H, dd),12.45 (1H, s); 19F NMR (471 MHz, DMSO-d6) −135.50 (1F, s), −70.49 (1F,s). m/z (ES⁺) [M+H]⁺=430.

Example 22:6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxamide

Ammonia (7 N Ammonia in MeOH) (31.3 ml, 218.90 mmol) was added to methyl6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxylate(intermediate 61) (0.470 g, 1.09 mmol) in a 40 mL scintillation vial,sealed and stirred at rt for 18 h. Complete conversion to desiredproduct by LCMS. The white solid was filtered to give 103 mg pureproduct. The filtrate was concentrated under vacuum, the resultingoff-white solid was slurry in about 5 mL methanol and filtered to obtainadditional pure product 298 mg. Both batches were combined to obtain6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxamide(example 22) (0.401 g, 88%). 1H NMR (500 MHz, DMSO-d6) 2.42 (3H, s),2.59 (4H, brs), 3.09-3.27 (4H, m), 3.70 (2H, s), 7.29 (1H, br t), 7.46(1H, brs), 7.49-7.58 (2H, m), 7.76 (1H, brs), 7.85 (1H, brd), 12.35 (1H,brs); 19F NMR (471 MHz, DMSO-d6) −135.49 (1F, s), −72.40 (1F, s); m/z(ES⁺) [M+H]⁺=415.

Intermediate 62: methyl 2-(4-bromo-3-fluoro-2-nitro-anilino)butanoate

DIPEA (165 ml, 942.91 mmol) was added slowly to a stirred solution of1-bromo-2,4-difluoro-3-nitro-benzene (intermediate 35) (74.8 g, 314.30mmol) and methyl 2-aminobutanoate, HCl (48.3 g, 314.30 mmol) in DMF (733mL) and the resulting solution was stirred at rt for 18 hours. DMF wasremoved on rocket evaporator, diluted with water and extracted withethyl acetate. After concentration the crude material was purified byflash silica chromatography, elution gradient 0 to 70% EtOAc in hexanes.Product fractions were concentrated under reduced pressure to affordmethyl 2-(4-bromo-3-fluoro-2-nitro-anilino)butanoate (intermediate 62)(49.4 g, 47%) as a red solid. 1H NMR (500 MHz, DMSO-d6) 0.82-0.98 (3H,m), 1.77-1.93 (2H, m), 3.70 (3H, d), 4.38-4.54 (1H, m), 6.77 (1H, br d),7.28 (1H, br d), 7.64-7.80 (1H, t); m/z (ES⁺) [M+H]⁺=335.

Intermediate 63:7-bromo-3-ethyl-8-fluoro-3,4-dihydro-1H-quinoxalin-2-one

Zinc (44.1 g, 674.07 mmol) was added portion wise (exothermic reaction)to a mixture of methyl 2-(4-bromo-3-fluoro-2-nitro-anilino)butanoate(intermediate 62) (50.2 g, 149.79 mmol) and ammonium chloride (64.1 g,1198.34 mmol) in MeOH (468 mL). The mixture was stirred at rt for 1 h.Solid was filtered off and washed with 20% MeOH in DCM. This materialwas dissolved in methanol (120 mL) and 4N HCl in dioxane (10 mL) wasadded and reaction was stirred for 30 min. Solvent was removed undervacuum, diluted with ethyl acetate and basified with sat NaHCO₃solution. Organic layer was separated, washed with water, dried oversodium sulphate and concentrated to give the crude product. The solidwas triturated with 100 mL methanol, stirred for 10 min and the lightbrown solid was filtered off to give7-bromo-3-ethyl-8-fluoro-3,4-dihydro-1H-quinoxalin-2-one (intermediate63) (39.8 g, 97%) product. 1H NMR (500 MHz, DMSO-d6) 0.92 (3H, t),1.49-1.77 (2H, m), 3.57-3.87 (1H, m), 6.24-6.62 (2H, m), 6.99 (1H, dd),10.44 (1H, s); m/z (ES⁺) [M+H]⁺=273.

Intermediate 64: 7-bromo-3-ethyl-8-fluoro-1H-quinoxalin-2-one

DDQ (29.7 g, 130.94 mmol) was added in one portion to a stirred solutionof 7-bromo-3-ethyl-8-fluoro-3,4-dihydro-1H-quinoxalin-2-one(intermediate 63) (29.8 g, 109.12 mmol) in DCM (546 mL) and theresulting solution was stirred at rt for 2 h. Solvent was removed undervacuum, and the solid was slurry with 150 mL of methanol and stirred for30 min. Solid was filtered off and washed with 30 mL methanol. Solid wastransferred to a 2 L round bottom flask; 200 mL water was added followby slow addition of 300 mL of sodium bicarbonate. After completeaddition the mixture was stirred for overnight at rt to give lightyellow slurry. Stirring was stopped and the aq layer was decanned. Solidwas collected by filtration and washed thoroughly with water to give7-bromo-3-ethyl-8-fluoro-1H-quinoxalin-2-one (intermediate 64) (24.45 g,83%) as yellow colored solid. 1H NMR (500 MHz, DMSO-d6) 1.22 (3H, t),2.81 (2H, q), 7.27-7.69 (2H, m), 12.59 (1H, brs); m/z (ES⁺) [M+H]⁺=271.

Intermediate 65: 3-ethyl-8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one

Xphos Pd G2 (1.121 g, 1.43 mmol) was added to a stirred degassedsolution of 7-bromo-3-ethyl-8-fluoro-1H-quinoxalin-2-one (intermediate64) (7.727 g, 28.50 mmol) and (tributylstannyl)methanol (10.98 g, 34.20mmol) in 1,4-dioxane (143 mL). The resulting solution was stirred at 80°C. for 6 hours. Solvent was removed under vacuum, 100 mL diethyl etherwas added, and the slurry was stirred for 30 min. Solid was filtered offand washed with 50 mL of diethyl ether to give3-ethyl-8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one (5.88 g, 93%)(intermediate 65) as off white solid. 1H NMR (500 MHz, DMSO-d6) 1.22(3H, t), 2.82 (2H, q), 4.64 (2H, br d), 5.40 (1H, t), 7.32 (1H, br t),7.55 (1H, d), 12.40 (1H, br s); m/z (ES⁺) [M+H]⁺=223.

Intermediate 66: 7-(bromomethyl)-3-ethyl-8-fluoro-1H-quinoxalin-2-one

Triethylphosphane (19.94 ml, 135.00 mmol) was added dropwise to astirred solution of3-ethyl-8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one (intermediate 65)(10 g, 45.00 mmol) and CBr₄ (49.2 g, 148.50 mmol) in DCM (355 mL) at 0°C. over a period of 5 minutes under nitrogen. Reaction was stirred at rtfor 1 h. DCM was removed under vacuum and residue was slurry in 150 mLdiethyl ether. The white ppt was filtered off and washed with 50 mLdiethyl ether. This solid was slurry with water (200 mL) and stirred for30 min. Solid was filtered off and washed thoroughly with water. Thesolid was dried under vacuum for overnight to give7-(bromomethyl)-3-ethyl-8-fluoroquinoxalin-2(1H)-one (intermediate 66)(11.38 g, 89%) as light brown solid. 1H NMR (500 MH z, DMSO-d6) 1.22(3H, t), 2.83 (2H, q), 4.81 (2H, s), 7.37 (1H, br t), 7.55 (1H, d),12.53 (1H, brs); m/z (ES⁺) [M+H]⁺=285.

Example 23:5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

DIPEA (20.90 ml, 119.64 mmol) was added to a stirred slurry of7-(bromomethyl)-3-ethyl-8-fluoroquinoxalin-2(1H)-one (intermediate 66)(11.37 g, 39.88 mmol) andN,6-dimethyl-5-piperazin-1-yl-pyridine-2-carboxamide, 2HCl (intermediate33) (14.09 g, 45.86 mmol) in acetonitrile (178 mL). The resultingsolution was stirred at 50° C. for 2 h. Reaction was complete. Half ofthe solvent was removed by evaporation, 10 mL sat sodium bicarbonate wasadded and mixture was stirred for 15 min. Solid was filtered off, washedwith water followed by 50 mL acetonitrile. Solid was dissolved inDCM/Methanol (˜9/1) and filtered through silica bed. Filtrate wasconcentrated to give the light yellow solid. This material wastriturated with ˜120 mL methanol, solid was filtered off and dried. LCMSstill shows ˜2.1% impurity (likely from the reagent). Material was againtriturated with acetonitrile and then with 3% methanol in acetonitrileto give ˜14 g white solid. Methanol (40 mL) was added and stirred for 3h. Solid was filtered off to give pure product5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 23) (12.26 g, 70%). 1HNMR (500 MHz, DMSO-d6) 1.23 (3H, t), 2.48(3H, s), 2.62 (4H, brs), 2.76-2.88 (5H, m), 2.95 (4H, brs), 3.73 (2H,s), 7.31 (1H, t), 7.47 (1H, d), 7.56 (1H, d), 7.79 (1H, d), 8.41 (1H,q), 12.44 (1H, s); m/z (ES⁺) [M+H]⁺=439.

Example 24:6-(difluoromethyl)-5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

DIPEA (0.049 mL, 0.28 mmol) was added to a stirred mixture of7-(bromomethyl)-3-ethyl-8-fluoroquinoxalin-2(1H)-one (intermediate 66)(40 mg, 0.14 mmol) and6-(difluoromethyl)-N-methyl-5-(piperazin-1-yl)picolinamide, 2HCl(intermediate 60) (48.1 mg, 0.14 mmol) in acetonitrile (2 mL) and Theresulting mixture was stirred at 70° C. for 2 hours. Reaction wasconcentrated and submitted to analytical group for purification(Purification conditions: the residue was purified by reverse phase C18column (eluted with 0 to 100% ACN/water/0.1% NH₄OH) which yield6-(difluoromethyl)-5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 24) (56.0 mg, 84%). 1H NMR (500 MHz, DMSO-d6) 1.23 (3H, t),2.65 (4H, br d), 2.77-2.86 (5H, m), 2.97-3.06 (4H, m), 3.73 (2H, s),7.00-7.26 (1H, t), 7.30 (1H, brd), 7.55 (1H, brd), 7.86 (1H, d), 8.09(1H, d), 8.39 (1H, q), 12.45 (1H, br d); m/z (ES⁺) [M+H]⁺=475.

Intermediate 67: methyl5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxylate

DIPEA (246 μl, 1.41 mmol) was added to a stirred slurry of7-(bromomethyl)-3-ethyl-8-fluoro-1H-quinoxalin-2-one (intermediate 66)(134 mg, 0.47 mmol) and methyl 5-(piperazin-1-yl)picolinate, 2HCl(intermediate 119) (138 mg, 0.47 mmol) in acetonitrile (2 mL). Theresulting solution was stirred at 50° C. for 2 h. Solvent was removedunder vacuum and the resulting residue was purified by flash silicachromatography, elution gradient 0 to 20% MeOH in DCM. Product fractionswere concentrated under reduced pressure to afford methyl5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxylate(intermediate 67) (0.142 g, 71.0%) as a white solid; m/z (ES⁺)[M+H]⁺=426. Example 25;5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxamide

Ammonia (7 N) in methanol (3 mL, 6.00 mmol) was added to methyl5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxylate(intermediate 67) (130 mg, 0.31 mmol). The resulting suspension wasstirred at 50° C. for 24 hours (sealed tube). Solvent was removed andthe resulting residue was purified by flash silica chromatography,elution gradient 0 to 35% MeOH in DCM. Product fractions wereconcentrated under reduced pressure to afford5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxamide(example 25) (0.079 g, 63%) as a pale yellow solid. 1H NMR (500 MHz,DMSO-d6) 1.23 (3H, t), 2.54-2.61 (4H, m), 2.83 (2H, q), 3.32-3.40 (4H,m), 3.70 (2H, s), 7.24-7.34 (2H, m), 7.38 (1H, dd), 7.56 (1H, d), 7.76(1H, br d), 7.84 (1H, d), 8.27 (1H, d), 12.44 (1H, brs); m/z (ES⁺)[M+H]⁺=411.

Intermediate 68: methyl5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxylate

Triethylphosphine (0.399 ml, 2.70 mmol) was added dropwise to a stirredsolution of 3-ethyl-8-fluoro-7-(hydroxymethyl)quinoxalin-2(1H)-one(intermediate 65) (0.2 g, 0.90 mmol) and CBr₄ (0.985 g, 2.97 mmol) inDCM (7.10 mL) at 0° C. over a period of 5 minutes under nitrogen.Reaction was stirred at rt for 1 h. DCM was removed under vacuum and theresulting solid was slurry in diethyl ether. The white ppt was filteredunder vacuum, washed with water followed by ether. The solid was driedunder vacuum for overnight (no heat) to give7-(bromomethyl)-3-ethyl-8-fluoroquinoxalin-2(1H)-one as a light brownsolid.

To the above crude product was added methyl6-methyl-5-(piperazin-1-yl)picolinate, 2HCl (intermediate 16) (278 mg,0.90 mmol), acetonitrile (10 mL) and N-ethyl-N-isopropylpropan-2-amine(785 μl, 4.51 mmol) and heated to 70° C. for 1 h. The reaction mixturewas cooled, concentrated, quenched with aq. NaHCO₃ solution (1 mL) andstirred for 1 h at rt. Water (3 mL) was added to the above mixture andstirred for 10 mins. The precipitate was filtered and washed with water(50 mL). The solid was purified via normal phase chromatography using0-10% MeOH in DCM. The isolated product was 89% pure by LCMS. The abovesolid was further purified using mass directed Prep HPLC using 20-40%acetonitrile in water with NH₄OH modifier to yield methyl5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxylate(intermediate 68) (115 mg, 0.262 mmol, 29%) as white solid with 93% LCMSpurity. 1H NMR (500 MHz, DMSO-d6) 1.23 (3H, t), 2.45-2.49 (3H, m),2.53-2.69 (4H, m), 2.83 (2H, q), 2.98 (4H, brs), 3.73 (2H, s), 3.83 (3H,s), 7.31 (1H, t), 7.45 (1H, d), 7.56 (1H, d), 7.86 (1H, d), 12.44 (1H,brs); 19F NMR (471 MHz, DMSO-d6) −135.54 (1F, s). m/z (ES⁺) [M+H]⁺=440.

Example 26:5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxamide

7 N ammonia in methanol (6.40 ml, 44.78 mmol) was added to methyl5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxylate(intermediate 68) (0.0984 g, 0.22 mmol) in a 40 mL scintillation vial,sealed and stirred at rt for 18 h. The reaction was concentrated undervacuum, added additional ammonia (6.40 ml, 44.78 mmol) solution andstirred at 50° C. for 16 h. The reaction was concentrated under vacuumand additional NH3 in methanol was added and stirred at rt for theweekend. Reaction was complete by LCMS. The reaction mixture wasconcentrated under vacuum, the resulting solid was slurry in diethylether. Solid was filtered and washed with additional ether and methanolto yield5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxamide(example 26) (0.095 g, 100%) as a white solid; 1H NMR (500 MHz, DMSO-d6)1.22 (3H, br t), 2.45-2.49 (3H, m), 2.52-2.68 (4H, m), 2.82 (2H, q),2.94 (4H, br s), 3.72 (2H, br s), 7.30 (1H, br t), 7.38-7.51 (2H, m),7.55 (1H, brd), 7.80 (2H, brd), 12.41 (1H, brs); 19F NMR (471 MHz,DMSO-d6) −135.53 (1F, s); m/z (ES⁺) [M+H]⁺=425.

Intermediate 69: 2-ethyl-5-fluoro-3-oxo-4H-quinoxaline-6-carbaldehyde

Dess-Martin periodinane (458 mg, 1.08 mmol) was added to3-ethyl-8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one (intermediate 65)(contaminated by its regio isomer3-ethyl-8-fluoro-5-(hydroxymethyl)-1H-quinoxalin-2-one) (160 mg, 0.72mmol) in DCM (5 mL). The resulting mixture was stirred at roomtemperature for 4 h. The solvent was evaporated to afford crude productwhich was purified by flash CIS-flash chromatography, elution gradient 5to 30% MeCN in water (0.4% FA). Pure fractions were evaporated todryness to afford 2-ethyl-5-fluoro-3-oxo-4H-quinoxaline-6-carbaldehyde(contaminated by its regio isomer3-ethyl-8-fluoro-2-oxo-1H-quinoxaline-5-carbaldehyde) (intermediate 69)(110 mg, 69%) as a yellow solid, m/z (ES⁺) [M+H]⁺=221.

Example 27:5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide

Titanium isopropoxide (64.5 mg, 0.23 mmol) was added to2-ethyl-5-fluoro-3-oxo-4H-quinoxaline-6-carbaldehyde (intermediate 69)(contaminated by its regio isomer3-ethyl-8-fluoro-2-oxo-1H-quinoxaline-5-carbaldehyde) (50 mg, 0.23 mmol)and 6-fluoro-N-methyl-5-(piperazin-1-yl)picolinamide (54.1 mg, 0.23mmol) in THF (3 mL). The resulting mixture was stirred at roomtemperature for 2 mins. Sodium triacetoxyborohydride (intermediate 32)(192 mg, 0.91 mmol) was added. The resulting mixture was stirred at roomtemperature for 16 h. The reaction mixture was quenched with MeOH (0.1mL). The solvent was evaporated to afford crude product. The cruderesidue was purified by preparative HPLC (Column: Xselect CSH OBD Column30*150 mm 5 um; Mobile Phase A: Water (0.05% TFA), Mobile Phase B: ACN;Flow rate: 60 mL/min; Gradient: 10% B to 20% B in 10 min; 254; 220 nm)and (Column: XBridge Shield RP18 OBD Column, 19*250 mm, 10 um; MobilePhase A: Water (10 MMOL/L NH₄HCO₃+0.1% NH₃.H₂O), Mobile Phase B: ACN;Flow rate: 20 mL/min; Gradient: 21 B to 95 B in 7 min; 254/220 nm.Fractions containing the desired compound were evaporated to dryness toafford5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide(example 27) (6 mg, 6%) as a white solid. 1H NMR (400 MHz, DMSO-d6) 1.22(3H, t), 2.56-2.64 (4H, m), 2.76 (3H, d), 2.82 (2H, q), 3.14-3.20 (4H,m), 3.71 (2H, s), 7.27-7.33 (1H, m), 7.53-7.59 (2H, m), 7.82-7.86 (1H,m), 8.38-8.45 (1H, m), 12.46 (1H, s); 19F NMR (376 MHz, DMSO-d6) −72.58,−135.51; m/z (ES⁺) [M+H]⁺=443.

Example 28:6-chloro-5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

Titanium isopropoxide (51.6 mg, 0.18 mmol) was added to2-ethyl-5-fluoro-3-oxo-4H-quinoxaline-6-carbaldehyde (intermediate 69)(contaminated by its regio isomer3-ethyl-8-fluoro-2-oxo-1H-quinoxaline-5-carbaldehyde) (40 mg, 0.18 mmol)and 6-chloro-N-methyl-5-(piperazin-1-yl)picolinamide (intermediate 30)(50 mg, 0.20 mmol) in THF (3 mL). The resulting mixture was stirred atroom temperature for 2 minutes. Sodium triacetoxyborohydride (154 mg,0.73 mmol) was added. The resulting mixture was stirred at roomtemperature for 16 hours. The reaction mixture was quenched with MeOH(0.1 mL) and evaporated to afford crude product. The crude product waspurified by preparative HPLC (Column: XBridge Shield RP18 OBD Column,30*150 mm, 5 um; Mobile Phase A: Water (0.05% NH₃H₂O), Mobile Phase B:ACN; Flow rate: 60 mL/min; Gradient: 21 B to 41 B in 7 min; 254/220 nm.Fractions containing the desired compound were evaporated to dryness toafford6-chloro-5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 28) (37.5 mg, 45%) as a white solid. 1H NMR (400 MHz, DMSO-d6)1.22 (3H, t), 2.57-2.65 (4H, m), 2.76-2.86 (5H, m), 3.05-3.15 (4H, m),3.72 (2H, s), 7.29 (1H, t), 7.55 (1H, d), 7.65 (1H, d), 7.93 (1H, d),8.40-8.45 (1H, m), 12.45 (1H, s); 19F NMR (376 MHz, DMSO-d6) −135.46;m/z (ES⁺) [M+H]⁺=459.

Example 29:5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

Titanium isopropoxide (51.6 mg, 0.18 mmol) was added to2-ethyl-5-fluoro-3-oxo-4H-quinoxaline-6-carbaldehyde (intermediate 69)(contaminated by its regio isomer3-ethyl-8-fluoro-2-oxo-1H-quinoxaline-5-carbaldehyde) (40 mg, 0.18 mmol)and N-methyl-5-(piperazin-1-yl)picolinamide (intermediate 31) (50 mg,0.23 mmol) in THF (3 mL). The resulting mixture was stirred at roomtemperature for 2 minutes. Sodium triacetoxyborohydride (154 mg, 0.73mmol) was added. The resulting mixture was stirred at room temperaturefor 16 hours. The reaction mixture was quenched with MeOH (0.1 mL) andconcentrated to afford crude product. The crude product was purified bypreparative HPLC (Column: Xselect CSH OBD Column 30*150 mm 5 um, n;Mobile Phase A: Water (0.1% FA), Mobile Phase B: ACN; Flow rate: 60mL/min; Gradients B to 17 B in 7 min; 254; 220 nm. Fractions containingthe desired compound were evaporated to dryness to afford5-[4-[(2-ethyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 29) (17.29 mg, 22%) as a white solid. 1H NMR (400 MHz, DMSO-d6)1.22 (3H, t), 2.53-2.63 (4H, m), 2.74-2.87 (5H, m), 3.05-3.15 (4H, m,merged into water peak), 3.69 (2H, s), 7.29 (1H, t), 7.37 (1H, dd), 7.54(1H, d), 7.81 (1H, d), 8.25 (1H, d), 8.35-8.42 (1H, m), 12.44 (1H, s);19F NMR (376 MHz, DMSO-d6) −135.49; m/z (ES⁺) [M+H]⁺=425.

Intermediate 70: 5-fluoro-2-methyl-3-oxo-4H-quinoxaline-6-carbaldehyde

Dess-Martin periodinane (1.34 g, 3.16 mmol) was added to8-fluoro-7-(hydroxymethyl)-3-methyl-1H-quinoxalin-2-one (intermediate17) (contaminated with8-fluoro-5-(hydroxymethyl)-3-methyl-1H-quinoxalin-2-one) (0.33 g, 0.79mmol) in DCM (20 ml). The resulting mixture was stirred at roomtemperature for 6 hours. The reaction mixture was evaporated to affordcrude product. The crude product was purified by flash C18-flashchromatography, elution gradient 5 to 30% MeCN in water (0.4% FA). Purefractions were evaporated to dryness to afford5-fluoro-2-methyl-3-oxo-4H-quinoxaline-6-carbaldehyde (contaminated with8-fluoro-3-methyl-2-oxo-1H-quinoxaline-5-carbaldehyde) (intermediate 70)(0.300 g, 92%) as an off-white solid, m/z (ES⁺) [M+H]⁺=207.

Example 30:6-chloro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

Titanium isopropoxide (89 mg, 0.31 mmol) was added to5-fluoro-2-methyl-3-oxo-4H-quinoxaline-6-carbaldehyde (contaminated with8-fluoro-3-methyl-2-oxo-1H-quinoxaline-5-carbaldehyde) (intermediate 70)(150 mg, 0.36 mmol) and6-chloro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate30) (80 mg, 0.31 mmol) in THF (3 mL). The resulting mixture was stirredat room temperature for 20 minutes. Sodium triacetoxyborohydride (266mg, 1.26 mmol) was added. The resulting mixture was stirred at roomtemperature for 16 hours. The reaction mixture was quenched with MeOH(0.1 mL) and concentrated to afford crude product. The crude product waspurified by preparative HPLC (Column: XBridge Shield RP18 OBD Column,19*250 mm, 10 urn; Mobile Phase A: Water (10 mmol/L NH₄HCO₃+0.1%NH₃.H₂O), Mobile Phase B: MeOH-Preparative; Flow rate: 20 mL/min;Gradient: 57 B to 80 B in 7 min; 254/220 nm. Fractions containing thedesired compound were evaporated to dryness to afford6-chloro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 30) (35.6 mg, 25%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.42 (3H, s), 2.58-2.66 (4H, m), 2.79 (3H, d), 3.06-3.16 (4H, m), 3.72(2H, s), 7.30 (1H, t), 7.53 (1H, d), 7.65 (1H, d), 7.93 (1H, d),8.41-8.48 (1H, m), 12.47 (1H, s); 19F NMR (376 MHz, DMSO-d6) −135.45;m/z (ES⁺) [M+H]⁺=445.

Example 31:5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

Titanium isopropoxide (105 mg, 0.37 mmol) was added to5-fluoro-2-methyl-3-oxo-4H-quinoxaline-6-carbaldehyde (contaminated with8-fluoro-3-methyl-2-oxo-1H-quinoxaline-5-carbaldehyde) (intermediate 70)(150 mg, 0.36 mmol) andN,6-dimethyl-5-piperazin-1-yl-pyridine-2-carboxamide, HCl (intermediate33) (100 mg, 0.37 mmol) in THF (3 mL). The resulting mixture was stirredat rt for 2 minutes. Sodium triacetoxyborohydride (313 mg, 1.48 mmol)was added. The resulting mixture was stirred at room temperature for 16hours. The reaction mixture was quenched with MeOH (0.1 mL) andevaporated to afford crude product. The crude product was purified bypreparative HPLC (Column: XBridge Shield RP18 OBD Column, 30*150 mm, 5um; Mobile Phase A: Water (0.05% NH₃H₂O), Mobile Phase B: ACN; Flowrate: 60 mL/min; Gradient: 19 B to 39 B in 7 min; 254/220 nm. Fractionscontaining the desired compound were evaporated to dryness to afford5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 31) (12.39 mg, 8%) as an off-white solid. 1H NMR (400 MHz,DMSO-d6) 2.42 (3H, s), 2.48 (3H, s), 2.57-2.67 (4H, m), 2.80 (3H, d),2.90-2.98 (4H, m), 3.72 (2H, s), 7.30 (1H, t), 7.47 (1H, d), 7.52 (1H,d), 7.79 (1H, d), 8.39-8.46 (1H, m), 12.46 (1H, s); 19F NMR (376 MHz,DMSO-d6) −135.52; m/z (ES⁺) [M+H]⁺=425.

Example 32:5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

Titanium isopropoxide (103 mg, 0.36 mmol) was added to5-fluoro-2-methyl-3-oxo-4H-quinoxaline-6-carbaldehyde (contaminated with8-fluoro-3-methyl-2-oxo-1H-quinoxaline-5-carbaldehyde) (150 mg, 0.36mmol) and N-methyl-5-(piperazin-1-yl)picolinamide (intermediate 31) (80mg, 0.36 mmol) in THF (3 mL). The resulting mixture was stirred at roomtemperature for 2 minutes. Sodium triacetoxyborohydride (308 mg, 1.45mmol) was added. The resulting mixture was stirred at room temperaturefor 16 hours. The reaction mixture was quenched with MeOH (0.1 mL). Thereaction mixture was evaporated to afford crude product. The crudeproduct was purified by preparative HPLC (Column: Xbridge Phenyl OBDColumn, 5 um, 19*150 mm; Mobile Phase A: Water (0.05% TFA), Mobile PhaseB: MeOH-Preparative; Flow rate: 20 mL/min; Gradient: 24 B to 32 B in 12min; 254/220 nm and (Column: XBridge Shield RP18 OBD Column, 19*250 mm,10 um; Mobile Phase A: Water (10 mmol/L NH₄HCO₃+0.1% NH₃.H₂O), MobilePhase B: ACN; Flow rate: 20 mL/min; Gradient: 15 B to 30 B in 10 min;254/220 nm. Fractions containing the desired compound were evaporated todryness to afford5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(12.4 mg, 8%) as a white solid. 1H NMR (400 MHz, DMSO-d6) 2.42 (3H, s),2.55-2.60 (4H, m), 2.78 (3H, d), 2.90-2.98 (4H, m, merged into waterpeak), 3.70 (2H, s), 7.30 (1H, t), 7.38 (1H, dd), 7.52 (1H, d), 7.82(1H, d), 8.26 (1H, d), 8.38-8.43 (1H, m), 12.47 (1H, s); 19F NMR (376MHz, DMSO-d6) −135.48; m/z (ES⁺) [M+H]⁺=411.

Intermediate 72: 4-bromo-3-fluoro-benzene-L2-diamine

Iron powder (5.2 g, 93.11 mmol) was added to4-bromo-3-fluoro-2-nitro-aniline (intermediate 71) (7.3 g, 31.06 mmol)and HCl (10 mL, 100.00 mmol) (10 M) in MeOH (30 mL). The resultingmixture was stirred at room temperature for 18 hours. The solvent wasremoved under reduced pressure. The reaction mixture was basified withsaturated Na₂CO₃ solution (100 mL). The aqueous layer was extracted withEtOAc (2×100 mL). The organic layer was dried over Na₂SO₄, filtered andevaporated to afford 4-bromo-3-fluoro-benzene-1,2-diamine (intermediate72) (6.05 g, 95%) as a dark solid. 1H NMR (400 MHz, DMSO-d6) 4.66 (2H,s), 4.94 (2H, s), 6.30 (1H, dd), 6.56 (1H, dd); m/z (ES⁺) [M+H]⁺=205,207.

Intermediate 73: 7-bromo-8-fluoro-1H-quinoxalin-2-one

Ethyl 2-oxoacetate in toluene (6.41 g, 31.39 mmol) was added to4-bromo-3-fluoro-benzene-1,2-diamine (intermediate 72) (4.46 g, 21.75mmol) in toluene (30 mL). The resulting mixture was stirred at 100° C.for 30 minutes. The solvent was removed under reduced pressure. Thereaction mixture was diluted with (PE: 10 mL and EA: 2 mL). Theprecipitate was collected by filtration, washed with EtOAc (5 mL) anddried under vacuum to afford 7-bromo-8-fluoro-1H-quinoxalin-2-one(intermediate 73) (contaminated by 6-bromo-5-fluoro-1H-quinoxalin-2-one)(2.75 g, 52%) as an off-white solid, m/z (ES⁺) [M+H]⁺=243.

Intermediate 74: 8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one

CataCXium A-Pd-G2 (0.12 g, 0.18 mmol) was added to(tributylstannyl)methanol (1.25 g, 3.89 mmol) and7-bromo-8-fluoro-1H-quinoxalin-2-one (intermediate 73) (1 g, 2.06 mmol)(contaminated by 6-bromo-5-fluoro-1H-quinoxalin-2-one) in 1,4-dioxane(30 mL). The resulting mixture was stirred at 100° C. for 18 hours undernitrogen. The reaction mixture was quenched with saturated KF (10 mL),filtered and evaporated to afford crude product. The crude product waspurified by flash C18-flash chromatography, elution gradient 3 to 30%MeCN in water (0.1% formic acid). Pure fractions were evaporated todryness to afford 8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one(intermediate 74) (260 mg, 69%) (contaminated by5-fluoro-6-(hydroxymethyl)-1H-quinoxalin-2-one) as an off-white solid,m/z (ES⁺) [M+H]⁺=195.

Example 33:5-[4-[(5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

SOCl₂ (0.3 mL, 4.11 mmol) was added to8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one (intermediate 74) (158mg, 0.41 mmol) (contaminated by5-fluoro-6-(hydroxymethyl)-1H-quinoxalin-2-one) in DCM (3 mL). Theresulting mixture was stirred at room temperature for 1 h. The solventwas removed under reduced pressure. DIPEA (0.25 mL, 1.43 mmol) andN-methyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate 31) (141mg, 0.64 mmol) were added to the mixture in NMP (3.00 mL). The resultingmixture was stirred at 80° C. for 1 h. The crude product was purified bypreparative HPLC (Column: XBridge Prep OBD C18 Column, 19*250 mm, 5 um;Mobile Phase A: Water (10 mmol/L NH₄HCO₃+0.1% NH₃.H₂O), Mobile Phase B:ACN; Flow rate: 20 mL/min; Gradient: 18 B to 24 B in 9 min; 254; 220nm). Fractions containing the desired compound were evaporated todryness to afford5-[4-[(5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 33) (13.00 mg, 8%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.55-2.60 (4H, m), 2.77 (3H, d), 3.28-3.33 (4H, m), 3.71 (2H, s),7.30-7.42 (2H, m), 7.61 (1H, d), 7.82 (1H, d), 8.20 (1H, s), 8.25 (1H,d), 8.37-8.42 (1H, m); 19F NMR (376 MHz, DMSO-d6) −129.26; m/z (ES⁺)[M+H]⁺=397.

Example 34:6-chloro-5-[4-[(5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

SOCl₂ (0.3 mL, 4.11 mmol) was added to8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one (intermediate 74)(contaminated by 5-fluoro-6-(hydroxymethyl)-1H-quinoxalin-2-one) (143mg, 0.37 mmol) in DCM (3 mL). The resulting mixture was stirred at roomtemperature for 1 h. The solvent was removed under reduced pressure.DIPEA (0.25 mL, 1.43 mmol) and6-chloro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate30) (101 mg, 0.40 mmol) were added to the mixture in NMP (3.00 mL). Theresulting mixture was stirred at 80° C. for 1 h. The crude product waspurified by preparative HPLC (Column: XBridge Prep OBD C18 Column,19*250 mm, 5 um; Mobile Phase A: Water (10 MMOL/L NH₄HCO₃+0.1% NH₃.H₂O),Mobile Phase B: ACN; Flow rate: 20 mL/min; Gradient: 25 B to 28 B in 9min; 254/220 nm. Fractions containing the desired compound wereevaporated to dryness to afford6-chloro-5-[4-[(5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 34) (23.0 mg, 14%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.58-2.65 (4H, m), 2.78 (3H, d), 3.07-3.14 (4H, m), 3.73 (2H, s), 7.35(1H, dd), 7.61 (1H, d), 7.65 (1H, d), 7.93 (1H, d), 8.20 (1H, s),8.41-8.45 (1H, m), 12.58 (1H, s); 19F NMR (376 MHz, DMSO-d6) −135.18;m/z (ES⁺) [M+H]⁺=431.

Example 35:5-[4-[(5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

SOCl₂ (0.3 mL, 4.11 mmol) was added to8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one (intermediate 74)(contaminated by 5-fluoro-6-(hydroxymethyl)-1H-quinoxalin-2-one) (143mg, 0.37 mmol) (153 mg, 0.39 mmol) in DCM (3 mL). The resulting mixturewas stirred at room temperature for 1 h. The solvent was removed underreduced pressure. DIPEA (0.25 mL, 1.43 mmol) andN,6-dimethyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate 33)(137 mg, 0.58 mmol) in NMP (3 mL) were added to the mixture. Theresulting mixture was stirred at 80° C. for 1 h. The crude product waspurified by preparative HPLC (Column: XBridge Prep OBD C18 Column,19*250 mm, 5 um; Mobile Phase A: Water (10 MMOL/L NH₄HCO₃+0.1% NH₃.H₂O),Mobile Phase B: ACN; Flow rate: 20 mL/min; Gradient: 24 B to 28 B in 9min; 254/220 nm. Fractions containing the desired compound wereevaporated to dryness to afford5-[4-[(5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 35) (13.0 mg, 8%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.48 (3H, s), 2.56-2.65 (4H, s), 2.79 (3H, d), 2.92-2.97 (4H, m), 3.73(2H, s), 7.31-7.39 (1H, m), 7.47 (1H, d), 7.61 (1H, d), 7.78 (1H, d),8.19 (1H, s), 8.39-8.44 (1H, m), 12.55 (1H, s); 19F NMR (376 MHz,DMSO-d6) −135.25; m/z (ES⁺) [M+H]⁺=411.

Example 36:6-fluoro-5-[4-[(5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

SOCl₂ (0.3 mL, 4.11 mmol) was added to8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one (contaminated by5-fluoro-6-(hydroxymethyl)-1H-quinoxalin-2-one) (144 mg, 0.37 mmol) inDCM (3 mL). The resulting mixture was stirred at room temperature for 1h. The solvent was removed under reduced pressure. DIPEA (0.25 mL, 1.43mmol) and 6-fluoro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide(intermediate 32) (94 mg, 0.39 mmol) were added to the mixture in NMP(3.00 mL). The resulting mixture was stirred at 80° C. for 1 h. Thecrude product was purified by preparative HPLC (Column: XBridge Prep OBDC18 Column, 19*250 mm, 5 um; Mobile Phase A: Water (10 MMOL/LNH₄HCO₃+0.1% NH₃.H₂O), Mobile Phase B: ACN; Flow rate: 20 mL/min;Gradient: 23 B to 25 B in 9 min; 254/220 nm; RT1: 6.9, 8.46. Fractionscontaining the desired compound were evaporated to dryness to afford6-fluoro-5-[4-[(5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 36) (16.0 mg, 10%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.56-2.62 (4H, m), 2.76 (3H, d), 3.13-3.20 (4H, m), 3.71 (2H, d), 7.33(1H, dd), 7.55 (1H, t), 7.61 (1H, d), 7.83 (1H, dd), 8.19 (1H, s),8.37-8.43 (1H, m), 12.56 (1H, brs); 19F NMR (376 MHz, DMSO-d6) −72.57,−135.21; m/z (ES⁺) [M+H]⁺=415.

Example 37:5-[4-[[2-(difluoromethyl)-5-fluoro-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

A solution of iron(II) chloride (6.18 mg, 0.05 mmol) and zinc(II)difluoromethanesulfinate (86 mg, 0.29 mmol) in water (0.5 mL) was addedportion wise to a stirred solution of5-[4-[(5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 35) (40.0 mg, 0.10 mmol) and TFA (7.51 μl, 0.10 mmol) in DMSO(3 mL) at room temperature. Followed by addition of tert-butylhydroperoxide (9.44 μl, 0.10 mmol) and the resulting mixture was stirredat room temperature for 2 h. The crude product was purified bypreparative HPLC (column, Column: XBridge Prep OBD C18 Column 30×150 mm5 um; Mobile Phase A: Water (0.05% NH₃H₂O), Mobile Phase B: ACN; Flowrate: 60 mL/min; Gradient: 12% B to 32% B in 7 min; 254/220 nm; Rt: 6.07min. Fractions containing the desired compound were evaporated todryness to afford5-[4-[[2-(difluoromethyl)-5-fluoro-3-oxo-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 37) (2.2 mg, 5%) as a pale yellow solid. 1H NMR (400 MHz,DMSO-d6) 2.49 (3H, s), 2.60-2.65 (4H, m), 2.80 (3H, d), 2.92-2.99 (4H,m), 3.76 (2H, s), 7.08 (1H, t), 7.39 (1H, t), 7.48 (1H, d), 7.70 (1H,d), 7.79 (1H, d), 8.42 (1H, q), 13.01 (1H, s); 19F NMR (376 MHz,DMSO-d6) −124.324, −134.183; m/z (ES⁺) [M+H]⁺=461.

Intermediate 72: 4-bromo-3-fluoro-benzene-L2-diamine

Iron powder (3.56 g, 63.83 mmol) was added to4-bromo-3-fluoro-2-nitro-aniline (intermediate 71) (3.00 g, 12.77 mmol),concentrated hydrogen chloride (10.64 ml, 127.65 mmol) in MeOH (30 mL)at rt. The resulting mixture was stirred at rt for 16 h. The reactionmixture was diluted with water (100 mL) and extracted with ethyl acetate(100 mL×3). The organic layer was dried over MgSO₄, filtered andevaporated to afford 4-bromo-3-fluoro-benzene-1,2-diamine (intermediate72) (2.5 g, 96%). 1H NMR (400 MHz, DMSO-d6) 4.66 (2H, s), 4.94 (2H, s),6.30 (dd, 1H), 6.56 (dd, 1H); m/z (ES⁺) [M+H]⁺=205.

Intermediate 75: 7-bromo-8-fluoro-3-methoxy-1H-quinoxalin-2-one

Methyl 2,2,2-trimethoxyacetate (2.402 g, 14.63 mmol) was added to4-bromo-3-fluorobenzene-1,2-diamine (intermediate 72) (1.500 g, 7.32mmol), tris(((trifluoromethyl)sulfonyl)oxy)ytterbium (0.454 g, 0.73mmol) in toluene (20 mL) at room temperature. The resulting mixture wasstirred at 100° C. for 5 h. The solvent was removed under reducedpressure. The crude product was purified by reverse phase chromatographyon C18 column, elution gradient 5 to 70% MeCN in water. Pure fractionswere evaporated to dryness to afford7-bromo-8-fluoro-3-methoxy-1H-quinoxalin-2-one (intermediate 75) (0.650g, 32%) as a white solid. 1H NMR (300 MHz, DMSO-d6) 3.97 (3H, s), 7.31(1H, dd), 7.45 (1H, dd); m/z (ES⁺) [M+H]⁺=273.

Intermediate 76:8-fluoro-7-(hydroxymethyl)-3-methoxy-1H-quinoxalin-2-one

(tributylstannyl)methanol (882 mg, 2.75 mmol) was added to7-bromo-8-fluoro-3-methoxyquinoxalin-2(1H)-one (intermediate 75) (300.0mg, 1.1 mmol), cataCXium A-Pd-G2 (73 mg, 0.11 mmol) in 1,4-dioxane (20mL) at room temperature under nitrogen. The resulting mixture wasstirred at 100° C. for 16 h. The reaction mixture was quenched with sat.KF (10 mL) and then filtered. The solvent was removed under reducedpressure. The crude product was purified by reverse phase chromatographyon C18 column, elution gradient 5 to 100% MeOH in water. Pure fractionswere evaporated to dryness to afford8-fluoro-7-(hydroxymethyl)-3-methoxy-1H-quinoxalin-2-one (intermediate76) (130 mg, 53%) as a white solid. 1H NMR (300 MHz, DMSO-d6) 3.97 (3H,s), 4.88 (2H, d), 5.36 (1H, s), 7.27-7.32 (1H, m), 7.36 (1H, d), 12.45(1H, s); m/z (ES⁺) [M+H]⁺=225.

Intermediate 77: 7-(chloromethyl)-8-fluoro-3-methoxy-1H-quinoxalin-2-one

SOCl₂ (8 ml, 109.62 mmol) was added to8-fluoro-7-(hydroxymethyl)-3-methoxy-1H-quinoxalin-2-one (intermediate76) (50.0 mg, 0.22 mmol) in diethyl ether (50 mL) at room temperature.The resulting mixture was stirred at room temperature for 16 h. Thesolvent was removed under reduced pressure to afford7-(chloromethyl)-8-fluoro-3-methoxy-1H-quinoxalin-2-one (intermediate77) (66.7 mg, 122%, crude) as a yellow oil. The product was used in thenext step directly without further purification. 1H NMR (300 MHz,DMSO-d6) 3.97 (3H, s), 4.88 (2H, s), 7.27-7.42 (2H, m), 12.60 (1H, s)m/z (ES⁺) [M+H]⁺=243.

Example 38:5-[4-[(5-fluoro-2-methoxy-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate 31) (150mg, 0.68 mmol) was added to7-(chloromethyl)-8-fluoro-3-methoxy-1H-quinoxalin-2-one (intermediate77) (198 mg, 0.82 mmol), DIPEA (0.595 mL, 3.40 mmol) in MeCN (10 mL) atroom temperature. The resulting mixture was stirred at 60° C. for 16 h.The solvent was removed under reduced pressure. The crude product waspurified by flash CIS-flash chromatography, elution gradient 5 to 70%MeCN in water. Pure fractions were evaporated to dryness to afford theproduct (103.0 mg) as a yellow solid (80% purity by UV). Repurified byflash C18-flash chromatography, elution gradient 5 to 70% MeCN in water.Pure fractions were evaporated to dryness to afford5-[4-[(5-fluoro-2-methoxy-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 38) (36.0 mg, 12%) as a yellow solid. 1H NMR (300 MHz, DMSO-d6)2.51-2.60 (4H, m), 2.77 (3H, d), 3.18-3.45 (4H, m), 3.66 (2H, s), 3.95(3H, s), 7.10-7.27 (1H, m), 7.27-7.42 (2H, m), 7.81 (1H, d), 8.25 (1H,d), 8.39 (1H, q), 12.30 (1H, s); 19F NMR (282 MHz, DMSO-d6) −134.783;m/z (ES⁺) [M+H]⁺=427.

Example 39:6-fluoro-5-[4-[(5-fluoro-2-methoxy-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

SOCl₂ (0.065 mL, 0.89 mmol) was added to8-fluoro-7-(hydroxymethyl)-3-methoxy-1H-quinoxalin-2-one (intermediate76) (0.040 g, 0.18 mmol) in diethyl ether (10 mL) at room temperature.The resulting mixture was stirred at room temperature for 16 h. Thesolvent was removed under reduced pressure.6-fluoro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate32) (0.043 g, 0.18 mmol) and DIPEA (0.156 mL, 0.89 mmol) in MeCN (10.00mL) were added to the above solid at room temperature. The resultingmixture was stirred at 60° C. for 16 h. The solvent was removed underreduced pressure. The crude product was purified by preparative HPLCcolumn, Column: XBridge Shield RP18 OBD Column, 19*250 mm, 10 um; MobilePhase A: Water (10 mmol/L NH₄HCO₃+0.1% NH₃.H₂O), Mobile Phase B: ACN;Flow rate: 20 mL/min; Gradient: 34 B to 48 B in 7 min; 254/220 nm; RT1:5.9. Fractions containing the desired compound were evaporated todryness to afford6-fluoro-5-[4-[(5-fluoro-2-methoxy-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 39) (0.020 g, 25%) as a white solid. 1H NMR (300 MHz, DMSO-d6)2.55-2.61 (4H, m), 2.75 (3H, d), 3.11-3.19 (4H, m), 3.67 (2H, s), 3.96(3H, s), 7.18-7.29 (1H, m), 7.35 (1H, d), 7.55 (1H, dd), 7.79-7.88 (1H,m), 8.41 (1H, d), 12.50 (1H, s); 19F NMR (282 MHz, DMSO-d6) −72.581,−134.799; m/z (ES⁺) [M+H]⁺=445.

Example 40:5-[4-[(5-fluoro-2-methoxy-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

N,6-dimethyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate 33)(0.097 g, 0.41 mmol) was added to7-(chloromethyl)-8-fluoro-3-methoxyquinoxalin-2(1H)-one (intermediate77) (0.100 g, 0.41 mmol), DIPEA (0.360 mL, 2.06 mmol) in MeCN (10 mL) atroom temperature. The resulting mixture was stirred at 60° C. for 16 h.The solvent was removed under reduced pressure. The crude product waspurified by preparative HPLC, Column: XBridge Prep OBD C18 Column,30×150 mm 5 um; Mobile Phase A: Water (0.05% NH₃H₂O), Mobile Phase B:ACN; Flow rate: 60 mL/min; Gradient: 10B to 30B in 7 min; 254/220 nm.Fractions containing the desired compound were evaporated to dryness toafford5-[4-[(5-fluoro-2-methoxy-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 40) (0.063 g, 35%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.48 (3H, s), 2.58-2.63 (4H, m), 2.80 (3H, d), 2.92-2.96 (4H, m), 3.69(2H, s), 3.97 (3H, s), 7.25 (1H, t), 7.36 (1H, d), 7.47 (1H, d), 7.79(1H, d), 8.43 (1H, q), 12.51 (1H, s); 19F NMR (376 MHz, DMSO-d6)−134.815; m/z (ES⁺) [M+H]⁺=441.

Example41:6-chloro-5-[4-[(5-fluoro-2-methoxy-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

SOCl₂ (0.065 mL, 0.89 mmol) was added to8-fluoro-7-(hydroxymethyl)-3-methoxy-1H-quinoxalin-2-one (intermediate76) (0.040 g, 0.18 mmol) in diethyl ether (10 mL) at room temperature.The resulting mixture was stirred at room temperature for 16 h. Thesolvent was removed under reduced pressure to afford crude7-(chloromethyl)-8-fluoro-3-methoxy-1H-quinoxalin-2-one (0.045 g, 0.18mmol). MeCN (10.00 mL) was added to the above solid followed by additionof 6-chloro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide(intermediate 30) (0.045 g, 0.18 mmol) and DIPEA (0.156 mL, 0.89 mmol).The resulting mixture was stirred at 80° C. for 16 hours. The solventwas removed under reduced pressure. The crude product was purified bypreparative HPLC column, Column: YMC-Actus Triart C18, 30*250.5 um;Mobile Phase A: Water (0.05% NH₃H₂O), Mobile Phase B: ACN; Flow rate: 60mL/min; Gradient: 21 B to 41 B in 7 min; 254, 220 nm; RT1: 6.18.Fractions containing the desired compound were evaporated to dryness toafford6-chloro-5-[4-[(5-fluoro-2-methoxy-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 41) (0.041 g, 50%) as a white solid. 1H NMR (300 MHz, DMSO-d6)2.56-2.66 (4H, m), 2.79 (3H, d), 3.06-3.16 (4H, m), 3.70 (2H, s), 3.97(3H, s), 7.19-7.30 (m, 1H), 7.36 (d, 1H), 7.66 (d, 1H), 7.93 (d, 1H),8.44 (d, 1H), 12.47 (s, 1H); 19F NMR (282 MHz, DMSO-d6) −134.746; m/z(ES⁺) [M+H]⁺=461.

Intermediate 78: 2-(4-bromo-3-methyl-2-nitro-anilino)butanoic Acid

2-aminobutanoic acid (0.793 g, 7.69 mmol) was added to1-bromo-4-fluoro-2-methyl-3-nitrobenzene (intermediate 2) (1.500 g, 6.41mmol), K₂CO₃ (2.66 g, 19.23 mmol) in DMF (20 mL) at room temperature.The resulting mixture was stirred at 100° C. for 6 h. The reactionmixture was poured into ice water, quenched slowly with 1 M HCl (20 mL)at 0° C. to give a yellow suspension. The solid was collected byfiltration, washed with water and dried to afford2-(4-bromo-3-methyl-2-nitro-anilino)butanoic acid (intermediate 78) (1.4g, 74%) as a yellow solid (not very pure, carried over to next stepwithout further purification), m/z (ES⁺) [M+H]⁺=317.

Intermediate 79:7-bromo-3-ethyl-8-methyl-3,4-dihydro-1H-quinoxalin-2-one

Iron powder (1.585 g, 28.38 mmol) was added slowly to2-(4-bromo-3-methyl-2-nitro-anilino)butanoic acid (intermediate 78)(1.800 g, 5.68 mmol), concentrated hydrogen chloride (4.73 ml, 56.76mmol) in MeOH (100 mL) at room temperature. The resulting mixture wasstirred at room temperature for 7 h. The reaction mixture was filtered.The solvent was removed under reduced pressure. The reaction mixture wasquenched with saturated Na₂CO₃ (40 mL) and extracted with EtOAc (3×50mL). The organic layer was dried over Na2SO₄, filtered and evaporated toafford brown solid. The crude product was purified by flash C18-flashchromatography, elution gradient 5 to 50% MeCN in water. Pure fractionswere evaporated to dryness to afford7-bromo-3-ethyl-8-methyl-3,4-dihydro-1H-quinoxalin-2-one (intermediate79) (650 mg, 43%) as a white solid. 1H NMR (300 MHz, DMSO-d6) 0.90 (3H,t), 1.43-1.72 (2H, m), 2.22 (3H, s), 3.56 (1H, ddd), 6.16 (1H, d), 6.56(1H, d), 6.97 (1H, d), 9.76 (1H, s); m/z (ES⁺) [M+H]⁺=269.

Intermediate 80: 7-bromo-3-ethyl-8-methyl-1H-quinoxalin-2-one

DDQ (1.316 g, 5.80 mmol) was added to7-bromo-3-ethyl-8-methyl-3,4-dihydro-1H-quinoxalin-2-one (intermediate79) (1.300 g, 4.83 mmol) in 1,4-dioxane (150 mL) at room temperature.The resulting mixture was stirred at room temperature for 3 h. Thesolvent was removed under reduced pressure. The reaction mixture wasquenched with saturated NaHCO₃ (150 mL). The precipitate was collectedby filtration. The solid was washed with water (10 mL×3) and dried undervacuum to afford the desired product7-bromo-3-ethyl-8-methyl-1H-quinoxalin-2-one (intermediate 80) (1.2 g,93%) as yellow solid. 1H NMR (300 MHz, DMSO-d6) 1.20 (3H, t), 2.44-2.53(3H, m), 2.78 (2H, q), 7.48 (2H, s), 11.74 (1H, s); m/z (ES⁺)[M+H]⁺=267.

Intermediate 81: 3-ethyl-7-(hydroxymethyl)-8-methyl-1H-quinoxalin-2-one

(tributylstannyl)methanol (1202 mg, 3.74 mmol) was added to7-bromo-3-ethyl-8-methylquinoxalin-2(1H)-one (intermediate 80) (400 mg,1.50 mmol), Pd(PPh₃)₄ (173 mg, 0.15 mmol) in 1,4-dioxane (40 mL) at roomtemperature under nitrogen. The resulting mixture was stirred at 60° C.for 16 h. The reaction mixture was quenched with KF (10 mL) and thesolid was filtered off. The solvent was removed under reduced pressure.The crude product was purified by flash C18-flash chromatography,elution gradient 5 to 100% MeOH in water. Pure fractions were evaporatedto dryness to afford3-ethyl-7-(hydroxymethyl)-8-methyl-1H-quinoxalin-2-one (intermediate 81)(100 mg, 31%) as a white solid. 1H NMR (400 MHz, DMSO-d6) 1.22 (3H, t),2.32 (3H, s), 2.81 (2H, q), 4.59 (2H, d), 5.25 (1H, s), 7.33 (1H, d),7.55 (1H, d); m/z (ES⁺) [M+H]⁺=219.

Example 42:5-[4-[(2-ethyl-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

HBr in AcOH (1 ml, 6.08 mmol) (33 w %) was added to3-ethyl-7-(hydroxymethyl)-8-methylquinoxalin-2(1H)-one (intermediate 81)(65.0 mg, 0.30 mmol) at rt. The resulting mixture was stirred at 60° C.for 2 h. The solvent was removed under reduced pressure.N,6-dimethyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate 33)(69.8 mg, 0.30 mmol) and DIPEA (0.156 ml, 0.89 mmol) in NMP (3 mL) wereadded to the above solid at room temperature. The resulting mixture wasstirred at 60° C. for 2 h. The crude product was purified by preparativeHPLC (column, Column: Sunfire prep C18 column, 30*150, 5 um; MobilePhase A: Water (0.1% FA), Mobile Phase B: ACN; Flow rate: 60 mL/min;Gradients B to 20 B in 7 min; 254/220 nm; RT1: 5.15; Fractionscontaining the desired compound were evaporated to dryness to afford5-[4-[(2-ethyl-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 42) (0.049 g, 38%) as a pale yellow solid. 1H NMR (300 MHz,DMSO-d6) 1.20 (3H, t), 2.42 (3H, s), 2.50 (3H, s), 2.53-2.59 (4H, m),2.73-2.86 (5H, m), 2.87-2.93 (4H, m), 3.61 (2H, s), 7.23 (1H, d), 7.45(1H, d), 7.52 (1H, d), 7.76 (1H, d), 8.39 (1H, d), 11.52 (1H, s); m/z(ES⁺) [M+H]⁺=435.

Example 43:5-[4-[(2-ethyl-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide

HBr in AcOH (1 ml, 6.08 mmol) (33 w %) was added to3-ethyl-7-(hydroxymethyl)-8-methyl-1H-quinoxalin-2-one (intermediate 81)(65.0 mg, 0.30 mmol) at room temperature. The resulting mixture wasstirred at 60° C. for 2 hours. The solvent was removed under reducedpressure. 6-fluoro-N-methyl-5-(piperazin-1-yl)picolinamide (intermediate32) (71.0 mg, 0.30 mmol) was added to the above solid, followed byaddition of DIPEA (0.156 ml, 0.89 mmol) in NMP (3 mL) at roomtemperature. The resulting mixture was stirred at 60° C. for 2 hours.The crude product was purified by preparative HPLC (column, Column:XBridge Prep OBD C18 Column, 30×150 mm 5 um; Mobile Phase A: Water(0.05% NH₃H₂O), Mobile Phase B: ACN; Flow rate: 60 mL/min; Gradient: 31B to 51 B in 7 min; 254/220 nm; RT1: 6.27; Fractions containing thedesired compound were evaporated to dryness to afford5-[4-[(2-ethyl-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide(example 43) (0.043 g, 33%) as a pale yellow solid. 1H NMR (300 MHz,DMSO-d6) 1.20 (3H, t), 2.41 (3H, s), 2.49-2.59 (4H, m), 2.70-2.81 (5H,m), 3.08-3.16 (4H, m), 3.59 (2H, s), 7.22 (1H, d), 7.47-7.60 (2H, m),7.82 (1H, dd), 8.37 (1H, d), 11.52 (1H, s); 19F NMR (282 MHz, DMSO-d6)−72.539; m/z (ES⁺) [M+H]⁺=439.

Example 44:5-[4-[(2-ethyl-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

HBr in AcOH (1 ml, 18.42 mmol) (33 wt %) was added to3-ethyl-7-(hydroxymethyl)-8-methyl-1H-quinoxalin-2-one (intermediate 81)(65.0 mg, 0.30 mmol) at room temperature. The resulting mixture wasstirred at 60° C. for 2 hours. The solvent was removed under reducedpressure. N-methyl-5-(piperazin-1-yl)picolinamide (intermediate 31)(65.6 mg, 0.30 mmol) and DIPEA (0.156 ml, 0.89 mmol) was added to theabove solid in NMP (3 mL) at room temperature. The resulting mixture wasstirred at 60° C. for 2 h. The crude product was purified by preparativeHPLC (Column: Sunfire prep C18 column, 30*150, 5 um; Mobile Phase A:Water (0.1% FA), Mobile Phase B: ACN; Flow rate: 60 mL/min; Gradients Bto 20 B in 7 min; 254/220 nm; RT1: 5.15; Fractions containing thedesired compound were evaporated to dryness to afford5-[4-[(2-ethyl-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 44) (0.014 g, 10%) as a pale yellow solid. 1H NMR (400 MHz,DMSO-d6) 1.16-1.26 (3H, m), 2.41 (3H, s), 2.49-2.59 (4H, m), 2.70-2.81(5H, m), 3.30-3.35 (4H, m, merged into water peak), 3.61 (2H, s), 7.25(1H, d), 7.38 (1H, d), 7.55 (1H, d), 7.82 (1H, d), 8.26 (1H, s), 8.38(1H, s), 11.53 (1H, s); m/z (ES⁺) [M+H]⁺=421.

Intermediate 82: tert-butyl4-[6-(ethylcarbamoyl)-2-fluoro-3-pyridyl]piperazine-1-carboxylate

tert-butyl4-(2-fluoro-6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate(intermediate 11) (500 mg, 1.47 mmol) was added to ethylamine in water(10 mL, 1.47 mmol) (65 wt %). The resulting mixture was stirred at roomtemperature for 2 h. The reaction went to completion. The precipitatewas collected by filtration, washed with water (2 mL×3) and dried undervacuum to afford tert-butyl4-[6-(ethylcarbamoyl)-2-fluoro-3-pyridyl]piperazine-1-carboxylate(intermediate 82) (0.515 g, 99%) as an off-white solid. 1H NMR (400 MHz,DMSO-d6) 1.09 (3H, t), 1.42 (9H, s), 3.11 (4H, t), 3.23-3.30 (2H, m),3.49 (4H, t), 7.59 (1H, dd), 7.85 (1H, d), 8.45 (1H, t); m/z (ES⁺)[M+H]⁺=353.

Intermediate 83:N-ethyl-6-fluoro-5-piperazin-1-yl-pyridine-2-carboxamide

tert-butyl4-[6-(ethylcarbamoyl)-2-fluoro-3-pyridyl]piperazine-1-carboxylate(intermediate 82) (536 mg, 1.52 mmol) was added to HCl in 1,4-dioxane (5mL, 20.00 mmol). The resulting mixture was stirred at room temperaturefor 1 h. DIPEA (5 mL) was added and the resulting mixture was stirred atroom temperature for 15 min. The reaction mixture was evaporated toafford crude product. The crude product was purified by flash C18-flashchromatography, elution gradient 5 to 50% MeCN in water (0.1% NH₄HCO₃).Pure fractions were evaporated to dryness to affordN-ethyl-6-fluoro-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate83) (0.368 g, 96%) as a yellow solid. The sample was not pure, carriedover to next step without further purification; m/z (ES⁺) [M+H]⁺=253.

Example 45:N-ethyl-6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxamide

Ph₃P (94 mg, 0.36 mmol) was added to CBr₄ (119 mg, 0.36 mmol),8-fluoro-7-(hydroxymethyl)-3-methylquinoxalin-2(1H)-one (intermediate17) (50 mg, 0.24 mmol) in CH₂Cl₂ (3 mL). The resulting mixture wasstirred at room temperature for 1 h. The solvent was removed underreduced pressure.N-ethyl-6-fluoro-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate83) (60 mg, 0.24 mmol) and DIPEA (1.5 mL, 8.59 mmol) in NMP (3 mL) wereadded to the mixture. The resulting mixture was stirred at 80° C. for 2h. The solvent was removed under reduced pressure. The crude product waspurified by flash C18-flash chromatography, elution gradient 0 to 25%MeCN in water (NH₄HCO₃). Pure fractions were evaporated to dryness toaffordN-ethyl-6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]pyridine-2-carboxamide(example 45) (2.60 mg, 3%) as a white solid. 1H NMR (300 MHz, DMSO-d6)1.09 (3H, t), 2.40 (3H, s), 2.52-2.62 (4H, m), 3.17-3.27 (4H, m), 3.25(2H, q), 3.68 (2H, s), 7.28 (1H, t), 7.48-7.59 (2H, m), 7.82 (1H, d),8.41 (1H, t), 12.48 (1H, s); 19F NMR (282 MHz, DMSO-d6) −72.58, −135.52;m/z (ES⁺) [M+H]⁺=443.

Intermediate 84: 5-bromo-N-ethyl-6-methyl-pyridine-2-carboxamide

Ethanamine in H₂O (3 mL, 2.20 mmol) (65 wt %) was added to methyl5-bromo-6-methyl-pyridine-2-carboxylate (intermediate 14) (505 mg, 2.20mmol). The resulting mixture was stirred at room temperature for 18 h.The solvent was removed under reduced pressure to afford5-bromo-N-ethyl-6-methyl-pyridine-2-carboxamide (intermediate 84) (0.500g, 94%) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 1.13 (3H, t), 2.66(3H, s), 3.26-3.39 (2H, m), 7.76 (1H, d), 8.18 (1H, d), 8.67-8.72 (1H,m); m/z (ES⁺) [M+H]⁺=243.

Intermediate 85: tert-butyl4-[6-(ethylcarbamoyl)-2-methyl-3-pyridyl]piperazine-1-carboxylate

Cs₂CO₃ (1.340 g, 4.11 mmol) was added to5-bromo-N-ethyl-6-methyl-pyridine-2-carboxamide (intermediate 84) (0.5g, 2.06 mmol), tert-butyl piperazine-1-carboxylate (0.575 g, 3.09 mmol),BINAP (0.128 g, 0.21 mmol) and Pd(OAc)₂ (0.046 g, 0.21 mmol) in1,4-dioxane (5 mL). The resulting mixture was stirred at 100° C. for 18h under nitrogen. The reaction mixture was diluted with EtOAc (10 mL),and washed sequentially with water (10 mL×2) followed by brine (10mL×1). The organic layer was dried over Na2SO₄, filtered and evaporatedto afford crude product. The crude product was purified by flash silicachromatography, elution gradient 0 to 40% EtOAc in petroleum ether. Purefractions were evaporated to dryness to afford tert-butyl4-[6-(ethylcarbamoyl)-2-methyl-3-pyridyl]piperazine-1-carboxylate(intermediate 85) (0.481 g, 67%) as a yellow solid. 1H NMR (300 MHz,Chloroform-d) 1.26 (3H, t), 1.49 (9H, s), 2.54 (3H, s), 2.85-2.98 (4H,m), 3.49 (2H, qd), 3.56-3.65 (4H, m), 7.32 (1H, d), 7.91-8.01 (2H, m);m/z (ES⁺) [M+H]⁺=349.

Intermediate 86:N-ethyl-6-methyl-5-piperazin-1-yl-pyridine-2-carboxamide

HCl in 1,4-dioxane (4 ml, 16.00 mmol, 4M) was added to tert-butyl4-[6-(ethylcarbamoyl)-2-methyl-3-pyridyl]piperazine-1-carboxylate(intermediate 85) (0.481 g, 1.38 mmol) in MeOH (10 mL). The resultingmixture was stirred at room temperature for 2 hours. The solvent wasremoved under reduced pressure. The reaction mixture was basified withDIPEA (1 mL) in MeOH (3 mL). The solvent was removed under reducedpressure. The crude product was purified by flash C18-flashchromatography, elution gradient 0 to 20% MeCN in water (NH₄HCO₃). Purefractions were evaporated to dryness to affordN-ethyl-6-methyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate86) (0.189 g, 55%) as a yellow oil. 1H NMR (400 MHz, DMSO-d6) 1.12 (3H,t), 2.81-2.92 (8H, m), 3.27-3.36 (5H, m), 7.46 (1H, d), 7.81 (1H, d),8.43 (1H, t); m/z (ES⁺) [M+H]⁺=249.

Example 46:N-ethyl-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxamide

Ph₃P (299 mg, 1.14 mmol) was added to8-fluoro-7-(hydroxymethyl)-3-methylquinoxalin-2(1H)-one (158 mg, 0.76mmol) (intermediate 17), CBr₄ (378 mg, 1.14 mmol) in CH₂Cl₂ (3.00 mL).The resulting mixture was stirred at room temperature for 1 h. Thesolvent was removed under reduced pressure.N-ethyl-6-methyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate86) (188 mg, 0.76 mmol) and DIPEA (1.5 mL, 8.59 mmol) were added to themixture in NMP (3 mL). The resulting mixture was stirred at 80° C. for 2h. The solvent was removed under reduced pressure. The crude product waspurified by flash C18-flash chromatography, elution gradient 0 to 25%MeCN in water (NH₄HCO₃). Pure fractions were evaporated to dryness toaffordN-ethyl-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-methyl-pyridine-2-carboxamide(example 46) (7.40 mg, 2%) as a white solid. 1H NMR (300 MHz, DMSO-d6)1.10 (3H, t), 2.40 (3H, s), 2.50 (3H, s), 2.54-2.64 (4H, m), 2.87-2.97(4H, m), 3.30 (2H, q), 3.70 (2H, s), 7.28 (1H, t), 7.47 (1H, d), 7.52(1H, d), 7.77 (1H, d), 8.42 (1H, t), 12.44 (1H, s); 19F NMR (282 MHz,DMSO-d6) −135.54; m/z (ES⁺) [M+H]⁺=439.

Intermediate 87:7-bromo-8-fluoro-3-(trifluoromethyl)-1H-quinoxalin-2-one

Ethyl 3,3,3-trifluoro-2-oxopropanoate (2.30 g, 13.52 mmol) was added to4-bromo-3-fluoro-benzene-1,2-diamine (intermediate 72) (2.20 g, 10.73mmol) in toluene (10 mL). The resulting mixture was stirred at 100° C.for 18 h. The solvent was removed under reduced pressure. The crudeproduct was purified by flash C18-flash chromatography, elution gradient3 to 70% MeCN in water (0.1% NH₄HCO₃). Pure fractions were evaporated todryness to afford7-bromo-8-fluoro-3-(trifluoromethyl)-1H-quinoxalin-2-one (intermediate87) (contaminated by6-bromo-5-fluoro-3-(trifluoromethyl)-1H-quinoxalin-2-one) (3.40 g, 501%)as an off-white solid, m/z (ES⁺) [M+H]⁺=311.

Intermediate 88:8-fluoro-7-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one

CataCxium A Pd G2 (53 mg, 0.08 mmol) was added to7-bromo-8-fluoro-3-(trifluoromethyl)-1H-quinoxalin-2-one (intermediate87) (contaminated by6-bromo-5-fluoro-3-(trifluoromethyl)-1H-quinoxalin-2-one) (0.5 g, 0.80mmol) and (Tributylstannyl)methanol (0.5 mL, 0.80 mmol) in 1,4-dioxane(15 mL). The resulting mixture was stirred at 80° C. for 18 h undernitrogen. The reaction mixture was quenched with saturated KF (1.25 mL).The reaction solution was collected by filtration, washed with dioxane(2.5 mL). The solvent of the combined organic layers was removed underreduced pressure. The crude product was purified by flash C18-flashchromatography, elution gradient 3 to 40% MeCN in water (0.1%, TFA).Pure fractions were evaporated to dryness to afford8-fluoro-7-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one(intermediate 88) (contaminated by5-fluoro-6-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one)(0.217 g, 51%) as an off-white solid, m/z (ES⁺) [M+H]⁺=263.

Example 47:5-[4-[[5-fluoro-3-oxo-2-(trifluoromethyl)-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

SOCl₂ (0.5 mL, 6.85 mmol) was added to8-fluoro-7-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one(intermediate 88) (contaminated by5-fluoro-6-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one) (160mg, 0.31 mmol) in Et₂O (5 mL). The resulting mixture was stirred at roomtemperature for 2 h. The solvent was removed under reduced pressure.DIPEA (4 mL, 22.90 mmol) andN,6-dimethyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate 33)(134 mg, 0.57 mmol) were added to the mixture in MeCN (10 mL). Theresulting mixture was stirred at room temperature for 24 h. The crudeproduct was purified by preparative HPLC (Column: XBridge BEH C18 OBDPrep Column, 5 μm, 19 mm 250 mm; Mobile Phase A: Water (10 mmol/LNH₄HCO₃+0.1% NH₃.H₂O), Mobile Phase B: ACN; Flow rate: 20 mL/min;Gradient: 24 B to 33 B in 10 min; 254/220 nm; RT1: 8.2/9.5) Fractionscontaining the desired compound were evaporated to dryness to afford5-[4-[[5-fluoro-3-oxo-2-(trifluoromethyl)-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(example 47) (8.8 mg, 6%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.50 (3H, s), 2.58-2.66 (4H, m), 2.79 (3H, d), 2.90-2.99 (4H, m), 3.77(2H, s), 7.41 (1H, t), 7.47 (1H, d), 7.72 (1H, d), 7.78 (1H, d),8.39-8.44 (1H, m), 13.21 (1H, brs); 19F NMR (376 MHz, DMSO-d6) −68.50,−133.81; m/z (ES⁺) [M+H]⁺=479.

Example 48:6-fluoro-5-[4-[[5-fluoro-3-oxo-2-(trifluoromethyl)-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

SOCl₂ (0.4 mL, 5.48 mmol) was added to8-fluoro-7-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one(intermediate 88) (contaminated by5-fluoro-6-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one) (120mg, 0.23 mmol) in Et₂O (5 mL). The resulting mixture was stirred at roomtemperature for 2 h. The solvent was removed under reduced pressure.DIPEA (2 mL, 11.45 mmol) and6-fluoro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate32) (156 mg, 0.65 mmol) were added to the mixture in MeCN (10 mL). Theresulting mixture was stirred at room temperature for 24 h. The crudeproduct was purified by preparative HPLC (Column: XBridge BEH C18 OBDPrep Column, 5 μm, 19 mm 250 mm; Mobile Phase A: Water (10 mmol/LNH₄HCO_(3+0.1)% NH₃.H₂O), Mobile Phase B: ACN; Flow rate: 20 mL/min;Gradient: 25 B to 37 B in 10 min; 254/220 nm; RT1: 7.58/8.97). Fractionscontaining the desired compound were evaporated to dryness to afford6-fluoro-5-[4-[[5-fluoro-3-oxo-2-(trifluoromethyl)-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 48) (8.9 mg, 8%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.58-2.65 (4H, m), 2.76 (3H, d), 3.14-3.21 (4H, m), 3.75 (2H, s), 7.39(1H, t), 7.56 (1H, dd), 7.71 (1H, d), 7.84 (1H, dd), 8.37-8.43 (1H, m),13.39 (1H, brs); 19F NMR (376 MHz, DMSO-d6) −68.48, −72.59, −133.78; m/z(ES⁺) [M+H]⁺=483.

Example 49:6-chloro-5-[4-[[5-fluoro-3-oxo-2-(trifluoromethyl)-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

SOCl₂ (0.4 mL, 5.48 mmol) was added to8-fluoro-7-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one(intermediate 88) (contaminated by5-fluoro-6-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one) (120mg, 0.23 mmol) in Et₂O (5 mL). The resulting mixture was stirred at roomtemperature for 2 h. The solvent was removed under reduced pressure.DIPEA (2 mL, 11.45 mmol) and6-chloro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide (intermediate30) (157 mg, 0.62 mmol) were added to the mixture in MeCN (10 mL). Theresulting mixture was stirred at room temperature for 24 h. The crudeproduct was purified by preparative HPLC (Column: XBridge Shield RP18OBD Column, 19*250 mm, 10 urn; Mobile Phase A: Water (10 MMOL/LNH₄HCO₃+0.1% NH₃.H₂O), Mobile Phase B: ACN; Flow rate: 20 mL/min;Gradient: 45 B to 57 B in 10 min; 254/220 nm). Fractions containing thedesired compound were evaporated to dryness to afford6-chloro-5-[4-[[5-fluoro-3-oxo-2-(trifluoromethyl)-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 49) (18 mg, 16%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.60-2.68 (4H, m), 2.78 (3H, d), 3.07-3.16 (4H, m), 3.77 (2H, s), 7.40(1H, t), 7.66 (1H, d), 7.72 (1H, d), 7.93 (1H, d), 8.40-8.43 (1H, m),13.25 (1H, brs); 19F NMR (376 MHz, DMSO-d6) −68.51, −133.73; m/z (ES⁺)[M+H]⁺=499.

Example 50:5-[4-[[5-fluoro-3-oxo-2-(trifluoromethyl)-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

SOCl₂ (0.4 mL, 5.48 mmol) was added to8-fluoro-7-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one(intermediate 88) (contaminated by5-fluoro-6-(hydroxymethyl)-3-(trifluoromethyl)-1H-quinoxalin-2-one) (120mg, 0.23 mmol) in Et₂O (5 mL). The resulting mixture was stirred at roomtemperature for 2. The solvent was removed under reduced pressure. DIPEA(2 mL, 11.45 mmol) and N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide(intermediate 31) (259 mg, 1.18 mmol) were added to the mixture in MeCN(10 mL). The resulting mixture was stirred at room temperature for 24 h.The crude product was purified by preparative HPLC (Column: XBridgeShield RP18 OBD Column, 19*250 mm, 10 urn; Mobile Phase A: Water (10mmol/L NH₄HCO₃+0.1% NH₃.H₂O), Mobile Phase B: ACN; Flow rate: 20 mL/min;Gradient: 15 B to 35 B in 10 min; 254/220 nm; RT1: 10.18/11.2).Fractions containing the desired compound were evaporated to dryness toafford5-[4-[[5-fluoro-3-oxo-2-(trifluoromethyl)-4H-quinoxalin-6-yl]methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(example 50) (6 mg, 6%) as a white solid. 1H NMR (400 MHz, DMSO-d6)2.51-2.57 (4H, m), 2.76 (3H, d), 3.25-3.34 (4H, m), 3.72 (2H, s), 7.30(1H, t), 7.39 (1H, dd), 7.65 (1H, d), 7.83 (1H, d), 8.27 (1H, d),8.36-8.41 (1H, m); 19F NMR (376 MHz, DMSO-d6) −68.34, −133.80; m/z (ES⁺)[M+H]⁺=465.

Intermediate 90: Methyl2-(4-bromo-3-fluoro-2-nitro-anilino)-3-methyl-butanoate

DIPEA (2.202 mL, 12.61 mmol) was added slowly to a stirred solution of1-bromo-2,4-difluoro-3-nitrobenzene (intermediate 35) (1 g, 4.20 mmol)and methyl valinate, HCl (intermediate 89) (0.704 g, 4.20 mmol) in DMF(6 mL). The resulting solution was stirred at rt for 18 hours (completeconversion to desired product by LCMS). Reaction mixture wasconcentrated, diluted with water and extracted with ethyl acetate,organic layer was dried over sodium sulphate, filtered and concentratedunder vacuum. The crude product was purified via normal phasechromatography with hexane: Ethyl acetate to yield methyl2-(4-bromo-3-fluoro-2-nitro-anilino)-3-methyl-butanoate (0.763 g, 52.0%)(intermediate 90) as a bright orange solid. 1H NMR (500 MHz,DICHLOROMETHANE-d2) 1.00-1.14 (6H, m), 2.20-2.35 (1H, m), 3.78 (3H, s),4.06 (1H, dd), 6.52 (1H, br d), 7.39 (1H, br d), 7.52 (1H, dd); 19F NMR(471 MHz, DICHLOROMETHANE-d2) −109.33 (1F, s); m/z (ES⁺) [M+H]⁺=349.

Intermediate 91:7-bromo-8-fluoro-3-isopropyl-3,4-dihydro-1H-quinoxalin-2-one

Zinc powder (1.143 g, 17.48 mmol) was added to a mixture of methyl2-(4-bromo-3-fluoro-2-nitro-anilino)-3-methyl-butanoate (0.763 g, 2.19mmol) (intermediate 90) and ammonium chloride (0.935 g, 17.48 mmol) inMeOH (12 mL) and water (0.3 mL) at 0° C. portion-wise (exothermicreaction), the mixture was stirred at rt for 2 h (No SM remaining,complete disappearance of orange coloration is indicative of reactioncompletion). Zn was filtered off, the solid cake was washed with 20%MeOH in DCM and the filtrate was concentrated under vacuum. Water wasadded to the above crude product and the product was extracted into theethyl acetate layer. The organic layer was dried and concentrated undervacuum to furnish a colorless oil. The crude product was slurried in 1:1ethylacetate:methanol, 0.5 mL 4N HCl in dioxane was added and thereaction was stirred for 1 h (No uncyclized product remaining). Thereaction mixture was concentrated to yield7-bromo-8-fluoro-3-isopropyl-3,4-dihydro-1H-quinoxalin-2-one(intermediate 91). The crude product was subjected to reagents for thenext step without any further purification assuming the yield of thisreaction to be 100%. m/z (ES⁺) [M+H]⁺=287.

Intermediate 92: 7-bromo-8-fluoro-3-isopropyl-1H-quinoxalin-2-one

4,5-dichloro-3,6-dioxocyclohexa-1,4-diene-1,2-dicarbonitrile (595 mg,2.62 mmol) was added in one portion to a stirred solution of7-bromo-8-fluoro-3-isopropyl-3,4-dihydroquinoxalin-2(1H)-one (627 mg,2.18 mmol) (intermediate 91) in DCM (20 mL). The resulting slurry wasstirred at rt for 2 hours (complete conversion to desired product byLCMS). The reaction mixture was concentrated under vacuum and quenchedwith saturated aq. sodium bicarbonate solution. The above slurry wasstirred at rt for overnight and the solid was filtered off. The filteredsolid was washed thoroughly with water followed by diethyl ether anddried to give 7-bromo-8-fluoro-3-isopropyl-1H-quinoxalin-2-one (0.425 g,68.3%) (intermediate 92) as an off-white solid. 1H NMR (500 MHz,DMSO-d6) 1.22 (6H, d), 3.36-3.52 (1H, m), 7.45-7.58 (2H, m), 12.62 (1H,br s); 19F NMR (471 MHz, DMSO-d6) −124.16 (1F, s); m/z (ES⁺) [M+H]⁺=285.

Intermediate 93:8-fluoro-7-(hydroxymethyl)-3-isopropyl-1H-quinoxalin-2-one

Xphos Pd G2 (103 mg, 0.13 mmol) was added to a stirred degassed solutionof 7-bromo-8-fluoro-3-isopropylquinoxalin-2(1H)-one (375 mg, 1.32 mmol)(intermediate 92) and (tributylstannyl)methanol (507 mg, 1.58 mmol) in1,4-dioxane (6.58 mL). The resulting solution was stirred at 80° C. for16 hours. The reaction mixture was concentrated under vacuum, andpurified via normal phase chromatography using 0-10% MeOH in DCM toyield 8-fluoro-7-(hydroxymethyl)-3-isopropyl-1H-quinoxalin-2-one (0.255g, 82%) (intermediate 93) as a white solid. 1H NMR (500 MHz, DMSO-d6)1.22 (6H, d), 3.39-3.52 (1H, m), 4.64 (2H, d), 5.41 (1H, t), 7.33 (1H,s), 7.55 (1H, d), 12.42 (1H, brs); 19F NMR (471 MHz, DMSO-d6) −137.71(1F, s); m/z (ES⁺) [M+H]⁺=237.

Intermediate 94:7-(bromomethyl)-8-fluoro-3-isopropyl-1H-quinoxalin-2-one

Triethylphosphane (0.477 ml, 3.23 mmol) was added dropwise to a stirredsolution of 8-fluoro-7-(hydroxymethyl)-3-isopropylquinoxalin-2(1H)-one(0.2541 g, 1.08 mmol) (intermediate 93) and CBr4 (1.177 g, 3.55 mmol) inDCM (8.49 mL) at 0° C. over a period of 5 minutes under nitrogen. Thereaction mixture was stirred at rt for 1 h, DCM was removed under vacuumand the resulting solid was slurried in diethyl ether. The white ppt wasfiltered under vacuum, washed with water followed by ether. The solidwas dried under vacuum for overnight (no heat) to give7-(bromomethyl)-8-fluoro-3-isopropyl-1H-quinoxalin-2-one (0.313 g, 97%)(intermediate 94) as light brown solid, m/z (ES⁺) [M+H]⁺=299.

Example 51:6-fluoro-5-[4-[(5-fluoro-2-isopropyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

To 7-(bromomethyl)-8-fluoro-3-isopropylquinoxalin-2(1H)-one (100 mg,0.33 mmol) (intermediate 94) was added6-fluoro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide, 2HCl (104 mg,0.33 mmol) (intermediate 32), acetonitrile (5 mL) andN-ethyl-N-isopropylpropan-2-amine (291 μL, 1.67 mmol) and heated to 70°C. LCMS indicated complete disappearance of SM and formation of desiredproduct after 1 h. The reaction mixture was cooled, concentrated,quenched with aq NaHCO₃ solution (1 mL) and stirred for 1 h at rt. Water(3 mL) was added to the above mixture and stirred for 10 mins. Theprecipitate was filtered and washed with copious amounts of water (50mL). The solid was purified via normal phase chromatography using 0-10%MeOH in DCM to yield6-fluoro-5-[4-[(5-fluoro-2-isopropyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(0.050 g, 32.8%) (Example 51) as a white solid. 1H NMR (500 MHz,DMSO-d6) 1.22 (6H, d), 2.53-2.65 (4H, m), 2.77 (3H, d), 3.12-3.24 (4H,m), 3.36-3.52 (1H, m), 3.71 (2H, s), 7.30 (1H, t), 7.52-7.59 (2H, m),7.84 (1H, d), 8.36-8.41 (1H, m), 12.46 (1H, brs); 19F NMR (471 MHz,DMSO-d6) −135.53 (1F, s), −72.59 (1F, s); m/z (ES⁺) [M+H]⁺=457.

Example 52:5-[4-[(5-fluoro-2-isopropyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

To 7-(bromomethyl)-8-fluoro-3-isopropylquinoxalin-2(1H)-one (109 mg,0.36 mmol) (intermediate 94), was addedN,6-dimethyl-5-(piperazin-1-yl)picolinamide, 2HCl (112 mg, 0.36 mmol)(intermediate 33), acetonitrile (5 mL) andN-ethyl-N-isopropylpropan-2-amine (317 μl, 1.82 mmol) and heated to 70C. LCMS indicated complete disappearance of SM and formation of desiredproduct after 1 h. The reaction mixture was cooled, concentrated,quenched with aq NaHCO₃ solution (1 mL) and stirred for 1 h at rt. Water(3 mL) was added to the above mixture and stirred for 10 mins. Theprecipitate was filtered and washed with copious amounts of water (50mL). The solid was purified via normal phase chromatography using 0-10%MeOH in DCM to yield5-[4-[(5-fluoro-2-isopropyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(0.057 g, 34.6%) as a white solid (Example 52). 1H NMR (500 MHz,DMSO-d6) 1.22 (6H, d), 2.46-2.49 (3H, m), 2.52-2.68 (4H, m), 2.80 (3H,d), 2.94 (4H, br s), 3.36-3.52 (1H, m), 3.73 (2H, s), 7.30 (1H, t), 7.47(1H, d), 7.56 (1H, d), 7.79 (1H, d), 8.37-8.44 (1H, m), 12.46 (1H, s);19F NMR (471 MHz, DMSO-d6) −135.55 (1F, s); m/z (ES⁺) [M+H]⁺=453.

Example 53:5-[4-[(5-fluoro-2-isopropyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

To 7-(bromomethyl)-8-fluoro-3-isopropylquinoxalin-2(1H)-one (100 mg,0.33 mmol) (intermediate 94), was addedN-methyl-5-(piperazin-1-yl)picolinamide, 2HCl (98 mg, 0.33 mmol)(intermediate 31), acetonitrile (5 mL) andN-ethyl-N-isopropylpropan-2-amine (291 μl, 1.67 mmol) and heated to 70°C. LCMS indicated complete disappearance of SM and formation of desiredproduct after 1 h. The reaction mixture was cooled, concentrated,quenched with aq NaHCO₃ solution (1 mL) and stirred for 1 h at rt. Water(3 mL) was added to the above mixture and stirred for 10 mins. Theprecipitate was filtered and washed with copious amounts of water (50mL). The solid was purified via normal phase chromatography using 0-10%MeOH in DCM to yield5-[4-[(5-fluoro-2-isopropyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(0.052 g, 35.5%) (Example 53) as a white solid. 1H NMR (500 MHz,DMSO-d6) 1.22 (6H, d), 2.52-2.61 (4H, m), 2.78 (3H, d), 3.26-3.30 (4H,m), 3.36-3.52 (1H, m), 3.70 (2H, s), 7.31 (1H, t), 7.38 (1H, dd), 7.56(1H, d), 7.82 (1H, d), 8.26 (1H, d), 8.38 (1H, brd), 12.45 (1H, brs);19F NMR (471 MHz, DMSO-d6) −135.54 (1F, s); m/z (ES⁺) [M+H]⁺=439.

Intermediate 96: methyl2-(4-bromo-3-fluoro-2-nitro-anilino)-2-cyclopropyl-acetate

DIPEA (2.202 mL, 12.61 mmol) was added slowly to a stirred solution of1-bromo-2,4-difluoro-3-nitrobenzene (intermediate 35) (1 g, 4.20 mmol)and methyl 2-amino-2-cyclopropylacetate, HCl (intermediate 95) (0.696 g,4.20 mmol) in DMF (6 mL). The resulting solution was stirred at rt for18 hours (complete conversion to desired product by LCMS). The reactionmixture was concentrated, diluted with water and extracted with ethylacetate, organic layer was dried over sodium sulphate, filtered andconcentrated under vacuum. The crude product was purified via normalphase chromatography using hexane and ethyl acetate to yield methyl2-(4-bromo-3-fluoro-2-nitro-anilino)-2-cyclopropyl-acetate (0.635 g,43.5%) (intermediate 96) as a bright orange solid. 1H NMR (500 MHz,DICHLOROMETHANE-d2) 0.39-0.49 (1H, m), 0.54 (1H, td), 0.64-0.75 (2H, m),1.25-1.39 (1H, m), 3.74-3.83 (4H, m), 6.45 (1H, dd), 7.34 (1H, brd),7.52 (1H, dd). 19F NMR (471 MHz, DICHLOROMETHANE-d2) −109.53 (1F, s);m/z (ES⁺) [M+H]⁺=347.

Intermediate 97:7-bromo-3-cyclopropyl-8-fluoro-3,4-dihydro-1H-quinoxalin-2-one

Zinc powder (957 mg, 14.63 mmol) was added to a mixture of methyl2-((4-bromo-3-fluoro-2-nitrophenyl)amino)-2-cyclopropylacetate (635 mg,1.83 mmol) (intermediate 96) and ammonium chloride (783 mg, 14.63 mmol)in MeOH (12 mL) and water (0.3 mL) at 0° C. portion-wise (exothermicreaction), the mixture was stirred at rt for 2 h (No SM remaining,Complete disappearance of orange coloration is indicative of reactioncompletion). Zn was filtered off and the solid cake was washed with 20%MeOH in DCM. The filtrate was concentrated, the crude material showedmostly uncyclized product. Water was added to the above crude productand the product was extracted into the ethyl acetate layer. The organiclayer was dried and concentrated under vacuum to furnish an oil. Thismaterial was slurried in 1:1 ethylacetate:methanol, 0.5 mL 4 N HCl indioxane was added and the reaction mixture was stirred for 1 h (Nouncyclized product remaining). The reaction mixture was concentrated toyield 7-bromo-3-cyclopropyl-8-fluoro-3,4-dihydro-1H-quinoxalin-2-one(intermediate 97) as a grey solid. The crude product was subjected toreagents for the next step without any further purification assuming theyield of this reaction to be 100%. m/z (ES⁺) [M+H]⁺=285.

Intermediate 98: 7-bromo-3-cyclopropyl-8-fluoro-1H-quinoxalin-2-one

4,5-dichloro-3,6-dioxocyclohexa-1,4-diene-1,2-dicarbonitrile (499 mg,2.20 mmol) was added in one portion to a stirred solution of7-bromo-3-cyclopropyl-8-fluoro-3,4-dihydroquinoxalin-2(1H)-one (522 mg,1.83 mmol) (intermediate 97) in DCM (20 mL). The resulting slurry wasstirred at rt for 2 hours (complete conversion to desired product byLCMS). The reaction mixture was concentrated under vacuum and quenchedwith saturated aq. sodium bicarbonate solution. The above slurry wasstirred at rt for overnight and the solid was filtered off. The solidwas washed thoroughly with water followed by diethyl ether and dried togive 7-bromo-3-cyclopropyl-8-fluoro-1H-quinoxalin-2-one (0.382 g, 73.7%)(intermediate 98) as an off-white solid, m/z (ES⁺) [M+H]⁺=283.

Intermediate 99:3-cyclopropyl-8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one

Xphos Pd G2 (92 mg, 0.12 mmol) was added to a stirred degassed solutionof 7-bromo-3-cyclopropyl-8-fluoroquinoxalin-2(1H)-one (332 mg, 1.17mmol) (intermediate 98) and (tributylstannyl)methanol (452 mg, 1.41mmol) in 1,4-dioxane (5.86 mL) and the resulting solution was stirred at80° C. for 16 hours. The reaction mixture was concentrated under vacuum,and purified via normal phase chromatography using 0-10% MeOH in DCM toyield 3-cyclopropyl-8-fluoro-7-(hydroxymethyl)-1H-quinoxalin-2-one(0.224 g, 82%) (intermediate 99) as a white solid. 1H NMR (500 MHz,DMSO-d6) 1.02-1.14 (4H, m), 2.52-2.73 (1H, m), 4.62 (2H, d), 5.38 (1H,t), 7.29 (1H, t), 7.43 (1H, d), 12.43 (1H, br s); 19F NMR (471 MHz,DMSO-d6) −137.67 (1F, s); m/z (ES⁺) [M+H]⁺=235.

Intermediate 100:7-(bromomethyl)-3-cyclopropyl-8-fluoro-1H-quinoxalin-2-one

Triethylphosphane (0.422 ml, 2.86 mmol) was added dropwise to a mixtureof 3-cyclopropyl-8-fluoro-7-(hydroxymethyl)quinoxalin-2(1H)-one (0.223g, 0.95 mmol) (intermediate 99) and CBr4 (1.043 g, 3.14 mmol) in DCM(7.52 mL) at 0° C. over a period of 5 minutes under nitrogen. Reactionwas stirred at rt for 1 h. DCM was removed under vacuum and theresulting solid was slurried in diethyl ether. The light greenish whiteppt was filtered under vacuum, washed with water followed by ether. Thesolid was dried under vacuum for overnight (no heat) to give7-(bromomethyl)-3-cyclopropyl-8-fluoro-1H-quinoxalin-2-one (0.193 g,68.2%) (intermediate 100) as a light green solid. 1H NMR (500 MHz,DMSO-d6) 1.03-1.17 (4H, m), 2.63-2.76 (1H, m), 4.79 (2H, s), 7.33 (1H,t), 7.43 (1H, d), 12.55 (1H, brs); 19F NMR (471 MHz, DMSO-d6) −133.65(1F, s); m/z (ES⁺) [M+H]⁺=297.

Example 54:5-[4-[(2-cyclopropyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide

To 7-(bromomethyl)-3-cyclopropyl-8-fluoroquinoxalin-2(1H)-one (75 mg,0.25 mmol) (intermediate 100), was added6-fluoro-N-methyl-5-(piperazin-1-yl)picolinamide, 2HCl (79 mg, 0.25mmol) (intermediate 32), acetonitrile (5 mL) andN-ethyl-N-isopropylpropan-2-amine (220 μl, 1.26 mmol) and heated to 70C. LCMS indicated complete disappearance of SM and formation of desiredproduct after 1 h. The reaction mixture was cooled, concentrated,quenched with aq NaHCO₃ solution (1 mL) and stirred for 1 h at rt. Water(3 mL) was added to the above mixture and stirred for 10 mins. Theprecipitate was filtered and washed with copious amounts of water (50mL). The solid was purified via normal phase chromatography using 0-10%MeOH in DCM to yield5-[4-[(2-cyclopropyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-6-fluoro-N-methyl-pyridine-2-carboxamide(0.048 g, 41.8%) (Example 54) as a white solid. 1H NMR (500 MHz,DMSO-d6) 1.04-1.13 (4H, m), 2.52-2.63 (4H, m), 2.71 (1H, s), 2.77 (3H,d), 3.12-3.21 (4H, m), 3.69 (2H, s), 7.26 (1H, t), 7.43 (1H, d), 7.55(1H, dd), 7.84 (1H, d), 8.39 (1H, brd), 12.46 (1H, brs); 19F NMR (471MHz, DMSO-d6) −135.52 (1F, s), −72.58 (1F, s); m/z (ES⁺) [M+H]⁺=455.

Example 55:5-[4-[(2-cyclopropyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

To 7-(bromomethyl)-3-cyclopropyl-8-fluoroquinoxalin-2(1H)-one (75 mg,0.25 mmol) (intermediate 100), was addedN,6-dimethyl-5-(piperazin-1-yl)picolinamide, 2HCl (78 mg, 0.25 mmol)(intermediate 33), acetonitrile (5 mL) andN-ethyl-N-isopropylpropan-2-amine (220 μL, 1.26 mmol) and heated to 70°C. LCMS indicated complete conversion to the desired product after 1 h.The reaction mixture was cooled, concentrated, quenched with aq NaHCO₃solution (1 mL) and stirred for 1 h at rt. Water (3 mL) was added to theabove mixture and stirred for 10 mins. The precipitate was filtered andwashed with copious amounts of water (50 mL). The solid was purified vianormal phase chromatography using 0-10% MeOH in DCM to yield5-[4-[(2-cyclopropyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(0.049 g, 43.1%) (Example 55) as a white solid. 1H NMR (500 MHz,DMSO-d6) 1.03-1.15 (4H, m), 2.46-2.49 (3H, m), 2.52-2.65 (4H, m),2.65-2.75 (1H, m), 2.80 (3H, d), 2.94 (4H, brs), 3.71 (2H, s), 7.26 (1H,t), 7.40-7.50 (2H, m), 7.79 (1H, d), 8.37-8.44 (1H, m), 12.46 (1H, s);19F NMR (471 MHz, DMSO-d6) −135.54 (1F, s); m/z (ES⁺) [M+H]⁺=451.

Example 56:5-[4-[(2-cyclopropyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

To 7-(bromomethyl)-3-cyclopropyl-8-fluoroquinoxalin-2(1H)-one (43 mg,0.14 mmol) (intermediate 100), was addedN-methyl-5-(piperazin-1-yl)picolinamide, 2HCl (42.4 mg, 0.14 mmol)(intermediate 31), acetonitrile (5 mL) andN-ethyl-N-isopropylpropan-2-amine (126 μl, 0.72 mmol) and heated to 70°C. LCMS indicated complete disappearance of SM and formation of desiredproduct after 1 h. The reaction mixture was cooled, concentrated,quenched with aq NaHCO₃ solution (1 mL) and stirred for 1 h at rt. Water(3 mL) was added to the above mixture and stirred for 10 mins. Theprecipitate was filtered and washed with copious amounts of water (25mL). The solid was purified via normal phase chromatography using 0-10%MeOH in DCM to yield5-[4-[(2-cyclopropyl-5-fluoro-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(0.020 g, 31.7%) (Example 56) as a white solid. 1H NMR (500 MHz,DMSO-d6) 1.03-1.16 (4H, m), 2.53-2.60 (4H, m), 2.65-2.80 (5H, m), 3.68(2H, s), 7.25 (1H, br t), 7.38 (1H, dd), 7.42 (1H, d), 7.82 (1H, d),8.25 (1H, d), 8.35-8.40 (1H, m), 12.38-12.51 (1H, m) (missing 3H likelyoverlaps with DMSO peak); 19F NMR (471 MHz, DMSO-d6) −135.52 (1F, s);m/z (ES⁺) [M+H]⁺=437

Intermediate 102: 7-bromo-3-methoxy-8-methyl-1H-quinoxalin-2-one

A mixture of 4-bromo-3-methylbenzene-1,2-diamine (1.75 g, 8.70 mmol)(Intermediate 101), methyl 2,2,2-trimethoxyacetate (2.86 g, 17.41 mmol)and ytterbium(III) trifluoromethanesulfonate (0.540 g, 0.87 mmol) intoluene (10 mL) in a sealed tube was degassed, back filled with N₂,stirred at 100° C. for overnight gave a brown suspension, LCMS indicatedthe formation of desired product, the mixture was cooled to rt, thesolid was collected by filtration, washed with methanol, dried to yield7-bromo-3-methoxy-8-methyl-1H-quinoxalin-2-one (1.2 g, 51.2%)(Intermediate 102) as a yellow solid (contaminated by about 8% of itsregio-isomer 6-bromo-3-methoxy-5-methylquinoxalin-2(1H)-one). 1H NMR(500 MHz, DMSO-d6) 2.50 (3H, br s), 3.97 (3H, s), 7.32 (1H, d), 7.45(1H, d), 11.79 (1H, br s); (m/z) (ES⁺) [M+H]⁺=269.

Intermediate 103:7-(hydroxymethyl)-3-methoxy-8-methyl-1H-quinoxalin-2-one

A mixture of (tributylstannyl)methanol (1.844 g, 5.74 mmol),7-bromo-3-methoxy-8-methyl-1H-quinoxalin-2-one (1.03 g, 3.83 mmol)(Intermediate 102) and Xphos Pd G2 (0.452 g, 0.57 mmol) in 1,4-dioxane(40 mL) was stirred at 80° C. for overnight under N₂ gave a darkmixture, LCMS indicated near full conversion. The solvent was removedunder reduced pressure, the residue was purified on silica gel column(eluted with 0 to 20% methanol in DCM), the fractions were concentratedto a yellow solid, the solid was checked by LCMS which indicated it wasnot very pure, the product was then slurried in 20 mL of methanol, thesolid was collected by filtration, dried to yield the product with 55%purity as a yellow solid (contaminated by 30% starting material and 9.5%de-brominated side product).

The solid obtained above was charged into a dry flask with 1,4-dioxane(40 mL), to the flask was added 900 mg of (tributylstannyl)methanol and300 mg of xphos Pd G2, the mixture was degassed, then stirred at 80° C.for overnight under N₂. The solvent was removed under reduced pressure,the mixture was purified on silica gel column (eluted with 0 to 20%methanol in DCM) to yield7-(hydroxymethyl)-3-methoxy-8-methyl-1H-quinoxalin-2-one (800 mg, 95%)(Intermediate 103) as a yellow solid with 80% purity by LCMS. 1H NMR(500 MHz, DMSO-d6) 2.32 (3H, s), 3.91-4.01 (3H, m), 4.56 (2H, d), 5.15(1H, t), 7.27 (1H, d), 7.37 (1H, d), 11.57 (1H, brs); (m/z) (ES⁺)[M+H]⁺=221.

Intermediate 104: 7-(bromomethyl)-3-methoxy-8-methyl-1H-quinoxalin-2-one

Triethylphosphane (294 μl, 2.04 mmol) was added dropwise to a suspensionof 7-(hydroxymethyl)-3-methoxy-8-methyl-1H-quinoxalin-2-one (300 mg,1.36 mmol) (Intermediate 103) and 1,1,2,2-tetrabromo-1,2-dichloroethane(875 mg, 2.11 mmol) in CH₂Cl₂ (20 mL) at 0° C. under N₂, the resultingmixture was then stirred at rt for 3.5 h, the solvent was removed underreduced pressure, the residue was suspended in ether (10 mL), filtered,the solid was washed with ether (10 mL×2), the solid was then suspendedin water (20 mL), filtered, washed with water (5 mL×3), dried to yield7-(bromomethyl)-3-methoxy-8-methyl-1H-quinoxalin-2-one (0.250 g, 64.8%)(Intermediate 104) as a light yellow solid, (m/z) (ES⁺) [M+H]⁺=285.

Example 57:5-[4-[(2-methoxy-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide

To a suspension of N,6-dimethyl-5-(piperazin-1-yl)picolinamide, 2HCl (83mg, 0.27 mmol) (Intermediate 33) and7-(bromomethyl)-3-methoxy-8-methyl-1H-quinoxalin-2-one (85 mg, 0.27mmol) (Intermediate 104) in acetonitrile (6 mL) was added DIPEA (236 μL,1.35 mmol), the resulting mixture was stirred at 70° C. for 2 h gave aclear solution, the mixture was cooled to rt gave a suspension, thesolid was collected by filtration, washed with water, acetonitrile,dried to yield5-[4-[(2-methoxy-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N,6-dimethyl-pyridine-2-carboxamide(0.064 g, 54.3%) (Example 57) as a white solid. 1H NMR (500 MHz,DMSO-d6) 2.43 (3H, s), 2.49 (3H, s), 2.57 (4H, brs), 2.80 (3H, d), 2.91(4H, brs), 3.60 (2H, s), 3.95 (3H, s), 7.18 (1H, d), 7.35 (1H, d), 7.46(1H, d), 7.78 (1H, d), 8.40 (1H, q), 11.58 (1H, br s); (m/z) (ES⁺)[M+H]⁺=437

Example 58:6-fluoro-5-[4-[(2-methoxy-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

To a suspension of 6-fluoro-N-methyl-5-(piperazin-1-yl)picolinamide,2HCl (84 mg, 0.27 mmol) (Intermediate 32) and7-(bromomethyl)-3-methoxy-8-methyl-1H-quinoxalin-2-one (85 mg, 0.27mmol) (Intermediate 104) in acetonitrile (6 mL) was added DIPEA (236 μL,1.35 mmol), the resulting mixture was stirred at 70° C. for 2 h gave asuspension, the mixture was cooled to rt, the solid was collected byfiltration, washed with water, acetonitrile, dried, the solid wassuspended in acetonitrile, filtered and dried to yield6-fluoro-5-[4-[(2-methoxy-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(0.073 g, 61.3%) (Example 58) as a beige colored solid. 1H NMR (500 MHz,DMSO-d6) 2.42 (3H, s), 2.55 (4H, brs), 2.76 (3H, d), 3.14 (4H, brs),3.58 (2H, s), 3.95 (3H, s), 7.17 (1H, br d), 7.35 (1H, br d), 7.50-7.63(1H, m), 7.83 (1H, br d), 8.38 (1H, br d), 11.58 (1H, s); (m/z) (ES⁺)[M+H]⁺=442.

Intermediate 106: methyl 6-bromo-5-fluoro-pyridine-2-carboxylate

Sulfuric acid (1.5 mL, 28.14 mmol) was added to a mixture of6-bromo-5-fluoropicolinic acid (500 mg, 2.27 mmol) (Intermediate 105) inMeOH (8 mL) slowly. The mixture was continued to stir at rt for 3 h gavea white suspension. LCMS indicated full conversion, the mixture waspoured into sat. aq NaHCO₃ solution, extracted with DCM (40 mL×2), theorganic layers were dried (anhydrous Na2SO₄), filtered and concentratedto yield methyl 6-bromo-5-fluoro-pyridine-2-carboxylate (532 mg, 100%)(Intermediate 106) as a white solid which was used for next step withoutfurther purification. 1H NMR (500 MHz, CHLOROFORM-d) 4.01 (3H, s), 7.55(1H, t), 8.15 (1H, dd); (m/z) (ES⁺) [M+H]⁺=236.

Intermediate 107: tert-butyl4-(2-bromo-6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate

A mixture of tert-butyl piperazine-1-carboxylate (8.21 g, 44.06 mmol),methyl 6-bromo-5-fluoro-pyridine-2-carboxylate (6.065 g, 25.92 mmol)(Intermediate 106) and potassium carbonate (4.66 g, 33.69 mmol) in DMF(60 mL) was stirred at 110° C. for 5 hours, LCMS indicated fullconversion. The mixture was cooled to rt, diluted with DCM and water,the layers were separated, the water layer was extracted with DCM twice,the organic layers were combined, dried (anhydrous Na2SO₄), filtered andconcentrated, the residue was purified on silica gel column (eluted with0 to 50% ethyl acetate in hexanes, UV at 221, 310 nm) to yield desiredproduct tert-butyl4-(2-bromo-6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate (7.68 g,74.1%) (Intermediate 107) as a white solid. 1H NMR (500 MHz,CHLOROFORM-d) 1.51 (9H, s), 3.14 (4H, br t), 3.60-3.71 (4H, m), 3.99(3H, s), 7.32 (1H, d), 8.08 (1H, d); (m/z) (ES⁺) [M+H]⁺=402.

Intermediate 108: tert-butyl4-[2-bromo-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate

tert-Butyl4-(2-bromo-6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate (7.67 g,19.16 mmol) (Intermediate 107) in methanamine (100 mL, 19.16 mmol) (33%in ethanol) in a sealed vessel was stirred at 60° C. for 4.5 h, LCMSindicated full conversion, the mixture was cooled to rt, concentrated,the residue was dissolved into DCM, washed with sat. NH₄Cl solution,dried (anhydrous Na₂SO₄), filtered and concentrated to yield tert-butyl4-[2-bromo-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate (7.48g, 98%) (Intermediate 108) as a white solid. 1H NMR (500 MHz,CHLOROFORM-d) 1.50 (9H, s), 3.02 (3H, d), 3.08 (4H, br t), 3.60-3.71(4H, m), 7.36 (1H, d), 7.68 (1H, brd), 8.11 (1H, d); (m/z) (ES⁺)[M+H]⁺=401.

Intermediate 109: tert-butyl4-[6-(methylcarbamoyl)-2-vinyl-3-pyridyl]piperazine-1-carboxylate

A mixture of tert-butyl4-[2-bromo-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate (1.344g, 3.37 mmol) (Intermediate 108), tributyl(vinyl)stannane (1.174 g, 3.70mmol) and Xphos Pd G2 (0.132 g, 0.17 mmol) in 1,4-dioxane (25 ml) wasstirred at 100° C. under N₂ for 2.5 hr, LCMS indicated full conversion.

The mixture was diluted with DCM, washed with sat. NH₄Cl, the organiclayer was dried (anhydrous Na₂SO₄), filtered and concentrated, theresidue was purified on silica gel column (eluted with 0 to 80% ethylacetate in hexanes, UV at 226, 293 nm) to yield tert-butyl4-[6-(methylcarbamoyl)-2-vinyl-3-pyridyl]piperazine-1-carboxylate (0.961g, 82%) (Intermediate 109) as a white solid. 1H NMR (500 MHz,CHLOROFORM-d) 1.50 (9H, s), 2.90-3.01 (4H, m), 3.05 (3H, d), 3.55-3.68(4H, m), 5.54 (1H, dd), 6.42 (1H, dd), 7.10 (1H, dd), 7.39 (1H, d), 7.98(1H, br d), 8.07 (1H, d); m/z (ES⁺) [M+H]⁺=346.6, 348.5.

Intermediate 110: tert-butyl4-[2-formyl-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate

Osmium tetroxide in H₂O (0.0435 mL, 6.00 μmol) was added to a solutionof tert-butyl4-[6-(methylcarbamoyl)-2-vinyl-3-pyridyl]piperazine-1-carboxylate (960mg, 2.77 mmol) (Intermediate 109), 2,6-lutidine (646 μl, 5.54 mmol) andsodium periodate (2371 mg, 11.08 mmol) in THF (25 mL)/water (5mL)/tert-butanol (2650 μL, 27.71 mmol) and stirred at rt for overnightgave a yellow suspension. LCMS and TLC indicated full conversion.Reaction was diluted with water and extracted with ethyl acetate. Afterconcentration the crude material was purified through silica column(eluted with 0 to 100% ethyl acetate in hexanes, UV at 226, 310 nm) toyield tert-butyl4-[2-formyl-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate(0.732 g, 76%) (Intermediate 110) as a yellow solid. 1H NMR (500 MHz,CHLOROFORM-d) 1.50 (9H, s), 3.07 (3H, d), 3.15-3.30 (4H, m), 3.63-3.79(4H, m), 7.48 (1H, d), 7.85 (1H, br d), 8.28 (1H, d), 10.10 (1H, s);(m/z) (ES⁺) [M+H]⁺=349.

Intermediate 111: tert-butyl4-[2-(difluoromethyl)-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate

tert-Butyl4-[2-formyl-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate (730mg, 2.10 mmol) (Intermediate 110) in CH₂Cl₂ (10 mL) was cooled to 0° C.,DAST (692 μL, 5.24 mmol) in DCM (5 mL) was added to the mixture, theresulting mixture was then stirred at rt for 4 h, TLC and LCMS indicatedfull conversion. The reaction mixture was quenched with sat. aq NaHCO₃solution dropwise, extracted with DCM, the organics were dried(anhydrous Na₂SO₄), filtered and concentrated, the residue was purifiedon silica gel column (eluted with 0 to 100% ethyl acetate in hexanes, UVat 254, 293 nm) to yield tert-butyl4-[2-(difluoromethyl)-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate(0.666 g, 86%) (Intermediate 111) as a white solid. 1H NMR (500 MHz,CHLOROFORM-d) 1.50 (9H, s), 2.93-3.02 (4H, m), 3.05 (3H, d), 3.57-3.72(4H, m), 6.99 (1H, t), 7.62 (1H, d), 7.92 (1H, br d), 8.27 (1H, d);(m/z) (ES⁺) [M+H]⁺=371.

Intermediate 60:6-(difluoromethyl)-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide.2HCl

HCl 4M in Dioxane (7 mL, 28.00 mmol) was added to a flask charged withtert-butyl4-[2-(difluoromethyl)-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate(665 mg, 1.80 mmol) (Intermediate 111) and a stir bar, the mixture wasstirred at rt for 1 hr gave a yellow suspension. The solvent wasremoved, the residue was diluted with ether, the solid was collected byfiltration, dried to yield6-(difluoromethyl)-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide,2HCl (0.617 g, 100%) (Intermediate 60) as an orange solid, (m/z) (ES⁺)[M+H]⁺=272.

Example 59:6-(difluoromethyl)-5-[4-[(2-methoxy-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

To a suspension of6-(difluoromethyl)-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide,2HCl (87 mg, 0.25 mmol) (Intermediate 60) and7-(bromomethyl)-3-methoxy-8-methyl-1H-quinoxalin-2-one (80 mg, 0.25mmol) (Intermediate 104) in acetonitrile (6 mL) was added DIPEA (222 μL,1.27 mmol), the resulting mixture was stirred at 70° C. for 2 h gave aclear solution, the mixture was cooled to rt gave a suspension, thesolid was collected by filtration, washed with acetonitrile, water,dried to yield6-(difluoromethyl)-5-[4-[(2-methoxy-5-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(0.070 g, 58.3%) (Example 59) as a white solid. 1H NMR (500 MHz,DMSO-d6) 2.43 (3H, s), 2.59 (4H, br s), 2.83 (3H, br d), 2.98 (4H, brs), 3.60 (2H, s), 3.95 (3H, s), 6.92-7.29 (2H, m), 7.35 (1H, d), 7.85(1H, br d), 8.08 (1H, d), 8.38 (1H, br d), 11.58 (1H, br s); ((m/z)(ES⁺) [M+H]⁺=473.

Example 60:6-(difluoromethyl)-5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide

A mixture of 7-(bromomethyl)-3,8-dimethyl-1H-quinoxalin-2-one (196 mg,0.73 mmol) (Intermediate 8),6-(difluoromethyl)-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide,2HCl (252 mg, 0.73 mmol) (Intermediate 60) and Et₃N (0.614 mL, 4.41mmol) in acetonitrile (25 mL) was stirred at 70° C. for 2 h gave a clearsolution, LCMS indicated full conversion. The mixture was cooled to rtovernight. A solid crystallized from the mixture, the solid wascollected by filtration, washed with acetonitrile, water, dried to yieldpart 1 of the product 141 mg, the filtrate was concentrated, purified onreverse phase gilson (eluted with 5 to 80% ACN/water/0.1% TFA) to yielda second portion of the product 92 mg as TFA salt. In total:6-(difluoromethyl)-5-[4-[(2,5-dimethyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(0.233 g, 64.0%) (Example 60) as an off white solid. 1H NMR (500 MHz,DMSO-d6) 2.40 (3H, s), 2.43 (3H, s), 2.60 (4H, brs), 2.83 (3H, d), 2.98(4H, brd), 3.63 (2H, s), 6.95-7.22 (1H, m), 7.23-7.29 (1H, m), 7.51 (1H,d), 7.85 (1H, d), 8.08 (1H, d), 8.38 (1H, br d), 11.54 (1H, br s); (m/z)(ES⁺) [M+H]⁺=457.

Intermediate 113: methyl 6-chloro-5-(piperazin-1-yl)picolinate

Piperazine (1.0 g, 11.61 mmol) was added to methyl6-chloro-5-fluoropicolinate (Intermediate 112, 1.0 g, 5.28 mmol) in MeCN(30 mL). The resulting mixture was stirred at 80° C. for 18 hours. Thesolvent was removed under reduced pressure. The crude product waspurified by reverse phase chromatography, elution gradient 5 to 60% MeCNin water (0.1% NH₄HCO₃). Pure fractions were evaporated to dryness toafford methyl 6-chloro-5-(piperazin-1-yl)picolinate (Intermediate 113,1.28 g, 95%) as a red oil. ¹H NMR (400 MHz, DMSO-d₆) δ 2.81-2.91 (4H,m), 3.04-3.08 (4H, m), 3.85 (3H, s), 7.61 (1H, d), 8.00 (1H, d) (NHproton is not shown); m/z (ES⁺) [M+H]⁺=256.

Intermediate 30: 6-chloro-N-methyl-5-(piperazin-1-yl)picolinamide

A 2 M solution of methylamine in THF (40 mL, 80.00 mmol) was added tomethyl 6-chloro-5-(piperazin-1-yl)picolinate (Intermediate 113, 1.26 g,4.93 mmol). The resulting mixture was stirred at 80° C. for 18 hours.The solvent was removed under reduced pressure. The crude product waspurified by reverse phase chromatography, elution gradient 5 to 60% MeCNin water (0.1% NH₄HCO₃). Pure fractions were evaporated to dryness toafford 6-chloro-N-methyl-5-(piperazin-1-yl)picolinamide (Intermediate30, 1.12 g, 89%) as a pale yellow oil. ¹H NMR (300 MHz, DMSO-d₆) δ 2.79(3H, d), 2.85-2.89 (4H, m), 2.97-3.02 (4H, m), 7.63 (1H, d), 7.94 (1H,d), 8.45 (1H, q) (Piperazine-NH proton is not shown); m/z (ES⁺)[M+H]⁺=255.

Intermediate 114: tert-butyl4-[2-fluoro-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate

tert-butyl4-(2-fluoro-6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate(Intermediate 11, 12.49 g, 36.80 mmol) in methylamine (120 mL, 36.80mmol, 33 wt % in ethanol) was stirred at rt for 24 hrs. (sealed tube).The solvent was removed under reduced pressure. The residue wasdissolved into DCM and filtered through silica gel bed and washed withethyl acetate. The filtrate was concentrated and dried under vacuum toafford tert-butyl4-[2-fluoro-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate(Intermediate 114, 12.45 g, 100%) as a yellow solid. 1H NMR (500 MHz,DMSO-d6) 1.42 (9H, s), 2.77 (3H, d), 3.04-3.16 (4H, m), 3.43-3.56 (4H,m), 7.59 (1H, dd), 7.80-7.93 (1H, m), 8.41 (1H, q); m/z (ES⁺)[M+H]⁺=340.

Intermediate 32:6-fluoro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide

HCl (4M in dioxane, 100 ml, 400.00 mmol) was added to a solution oftert-butyl4-[2-fluoro-6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate(Intermediate 114, 12.5 g, 36.94 mmol) in 1,4-dioxane (50 mL) at 0° C.the reaction was stirred for 5 h during which the temperature was warmedto room temperature to give a yellow suspension. The suspension wasdiluted with ether, solid was filtered off and washed with ether. Thissolid was dried under vacuum to afford6-fluoro-N-methyl-5-piperazin-1-yl-pyridine-2-carboxamide, 2HCl(Intermediate 32, 11.42 g, 99%) as a light-yellow solid. 1H NMR (500MHz, DMSO-d6) δ ppm 2.8 (d, J=4.6 Hz, 3H) 3.3 (br s, 4H) 3.4 (br d,J=4.4 Hz, 4H) 7.6-7.7 (m, 1H) 7.9 (d, J=8.1 Hz, 1H) 8.4 (brd, J=4.4 Hz,1H) 9.0-9.3 (m, 2H); m/z (ES⁺) [M+H]⁺=239

Intermediate 115: 5-bromo-N,6-dimethylpicolinamide

A 2 M solution of methylamine in THF (20 mL, 40.00 mmol) was added tomethyl 5-bromo-6-methylpicolinate (Intermediate 14, 2.0 g, 8.69 mmol)and the resulting mixture was stirred at 80° C. for 18 hours. Thesolvent was removed under reduced pressure. The crude product waspurified by reverse phase chromatography, elution gradient 5 to 80% MeOHin water (0.1% NH₄HCO₃). Pure fractions were evaporated to dryness toafford 5-bromo-N,6-dimethylpicolinamide (Intermediate 115, 1.5 g, 75%)as a pale yellow solid. ¹H NMR (400 MHz, DMSO-d₆) δ 2.65 (3H, s), 2.82(3H, d), 7.75 (1H, d), 8.17 (1H, d), 8.57-8.76 (1H, m); m/z (ES⁺)[M+H]⁺=229

Intermediate 116: tert-butyl4-(2-methyl-6-(methylcarbamoyl)pyridin-3-yl)piperazine-1-carboxylate

5-bromo-N,6-dimethylpicolinamide (Intermediate 115, 1.0 g, 4.37 mmol)was added to tert-butyl piperazine-1-carboxylate (0.894 g, 4.80 mmol),BINAP (0.272 g, 0.44 mmol), Pd(OAc)₂ (0.098 g, 0.44 mmol) and Cs₂CO₃(3.56 g, 10.91 mmol) in toluene (20 mL) under nitrogen. The resultingmixture was stirred at 80° C. for 16 hours. The solvent was removedunder reduced pressure. The crude product was purified by reverse phasechromatography, elution gradient 5 to 30% MeOH in water (0.4% HCO₂H).Pure fractions were evaporated to dryness to afford tert-butyl4-(2-methyl-6-(methylcarbamoyl)pyridin-3-yl)piperazine-1-carboxylate(Intermediate 116, 1.2 g, 82%) as a brown solid. ¹H NMR (300 MHz, CD₃OD)δ 1.50 (9H, s), 2.58 (3H, s), 2.92-3.00 (7H, m), 3.62 (4H, m), 7.50 (1H,d), 7.88 (1H, d); m/z (ES⁺) [M+H]⁺=335.

Intermediate 33: N, 6-dimethyl-5-(piperazin-1-yl)picolinamide

tert-butyl4-(2-methyl-6-(methylcarbamoyl)pyridin-3-yl)piperazine-1-carboxylate(Intermediate 115, 1.18 g, 3.53 mmol) was added to a 4 M solution of HClin the 1,4-dioxane (10 mL, 329.15 mmol). The resulting mixture wasstirred at room temperature for 1 hour. The precipitate was collected byfiltration, washed with petroleum ether (5 mL×2), Et₂O (5 mL×2), anddried under vacuum to afford N,6-dimethyl-5-(piperazin-1-yl)picolinamide(Intermediate 33, 0.77 g, 81%) as an yellow solid. ¹H NMR (300 MHz,CD₃OD) δ 2.86 (3H, s), 3.02 (3H, s), 3.42-3.54 (8H, m), 8.29 (2H, d);m/z (ES⁺) [M+H]⁺=235.

Intermediate 117: tert-butyl4-(6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate

Ruphos Pd G3 (4.07 g, 4.86 mmol) was added to a degassed mixture ofmethyl 5-bromopyridine-2-carboxylate (Intermediate 9, 30 g, 138.87mmol), tert-butyl piperazine-1-carboxylate (27.2 g, 145.81 mmol), Cs₂CO₃(90 g, 277.73 mmol) in 1,4-dioxane (200 mL) and the mixture was stirredat 110° C. for 6 hrs under N2 atmosphere. The mixture was then cooled toroom temperature, diluted with water, extracted with ethyl acetate (150ml×3). Combined organic layers were dried over anhydrous Na₂SO₄ andfiltered. To this filtrate was added3-(Diethylenetriamino)propyl-functionalized silica gel (12 g, 1.3 mmol/gloading) and the mixture was stirred at rt for 1 hr. The mixture wasfiltered, and the filtrate was concentrated to ˜100 mL. The crystallineyellow solid was filtered off, washed with ether and dried under vacuumto afford tert-butyl4-(6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate (Intermediate117, 26.36 g, 82 mmol, 59.1%) as a yellow solid. 1H NMR (500 MHz,CHLOROFORM-d) 1.50 (9H, s), 3.31-3.42 (4H, m), 3.56-3.68 (4H, m), 3.98(3H, s), 8.04 (1H, d), 8.37 (1H, d); m/z (ES⁺) [M+H]⁺=322.

Intermediate 118: tert-butyl4-[6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate

Methylamine (100 mL, 1155.26 mmol, 40% in water) was added to a solutionof tert-butyl 4-(6-methoxycarbonyl-3-pyridyl)piperazine-1-carboxylate(Intermediate 117, 36 g, 112.02 mmol) in MeOH (100 mL) and the reactionwas stirred at room temperature for 4 hs to give a white suspension. Themixture was concentrated, the residue was partitioned between sat. NH₄Clsolution and DCM, the layers were separated. The aqueous layer wasextracted with DCM, the organic layers were combined, washed with brine,dried over Na₂SO₄, filtered and concentrated to give tert-butyl4-[6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate (Intermediate118, 35.9 g, 100%) as a yellow solid. 1H NMR (500 MHz, CHLOROFORM-d)1.49 (9H, s), 3.02 (3H, d), 3.26-3.35 (4H, m), 3.58-3.67 (4H, m), 7.23(1H, dd), 7.81 (1H, brd), 8.07 (1H, d), 8.16 (1H, d); m/z (ES⁺)[M+H]⁺=321.

Intermediate 119: methyl 5-(piperazin-1-yl)picolinate

HCl 4M in Dioxane (20 ml, 576.01 mmol) was added to a mixture oftert-butyl 4-(6-(methoxycarbonyl)pyridin-3-yl)piperazine-1-carboxylate(Intermediate 117, 1.55 g, 4.82 mmol) in MeOH (2 mL) at 0° C., thereaction was stirred at r.t for 2 hr gave a suspension, LCMS indicatedfull conversion, the mixture was diluted with ether (˜80 ml), the solidwas collected by filtration, washed with ether, dried to yield methyl5-(piperazin-1-yl)picolinate (intermediate 119) (1.384 g, 98%) as ayellow solid. 1H NMR (500 MHz, DMSO-d6) 3.21 (4H, brs), 3.66 (4H, brd),3.83 (3H, s), 7.43-7.55 (1H, m), 7.95 (1H, brd), 8.43 (1H, brs), 9.49(2H, brs); (m/z) (ES+) [M+H]+=223.0.

Intermediate 31: carboxylateN-methyl-5-piperazin-1-yl-pyridine-2-carboxamide

HCl (4M in dioxane, 150 mL, 600.00 mmol) was added to a suspension oftert-butyl 4-[6-(methylcarbamoyl)-3-pyridyl]piperazine-1-carboxylate(Intermediate 118, 35.9 g, 112.05 mmol) in MeOH (50 mL) and theresulting orange suspension was stirred at rt for 4 hr. About 80 mL ofsolvent was removed under reduced pressure and the mixture was dilutedwith ether and hexanes (200 ml, 1/1). The solid was collected byfiltration, washed with hexanes, dried and dried under vacuum to affordN-methyl-5-piperazin-1-yl-pyridine-2-carboxamide, 2HCl salt(Intermediate 31, 37.0 g, 100%) as a yellow solid. 1H NMR (500 MHz,DMSO-d6) 2.79 (3H, d), 3.22 (4H, brs), 3.53-3.67 (4H, m), 7.51 (1H, dd),7.91 (1H, d), 8.33 (1H, d), 8.50 (1H, br s), 9.19-9.49 (2H, m); m/z(ES⁺) [M+H]⁺=221.

Example 61: Preparation of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideCrystalline Form B (Anhydrous Form)

Method 1

43 mg (0.10 mmol) of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(from e.g. Example 20) was suspended in 1.0 ml of MeOH and 0.11 ml of 1Mmethanesulfonic acid (MSA) aqueous solution was added to get a clearsolution. To the solution, 0.11 ml of 1N NaOH aqueous solution wasadded. White solid started to precipitate after completion of adding theNaOH solution. The slurry was stirred at the room temperature for 1 day.36 mg of the white solid was filtered and dried in air. XRPD shows thatthe solid is pure6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideForm B.

Method 2

Pyridine (93.5 g) was added to pure6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamidemesylate (4.67 kg, prepared via method 2 of Example 63) solution inwater (47.9 kg) and ethanol (38.0 kg) at 75±5° C., followed by6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideForm B seed (4.7 g) prepared according to method 1. The slurry wasstirred at 75±5° C. for 40 min then pyridine (651 g) solution in 50:50v:v water:ethanol (4.2 kg) was added gradually over 3 h 40 min. Theslurry was stirred at 75±5° C. for 50 min then 4-methylmorpholine (900g) solution in 50:50 v:v water:ethanol (4.1 kg) was added gradually over3 h 50 min. The slurry was stirred at 75±5° C. for 1 h 10 min, cooled to25±5° C. over 4 h 50 min, stirred at 25±5° C. for 15 h then filtered.The resulting solid was washed twice with 50:50 v:v water:ethanol (12.5kg×2) and then dried under vacuum at between 25° C. and 50° C. for 1 dayto give pure6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideForm B (3.54 kg) in 93% yield.

Form B from method 1 was analyzed by XRPD and the results are tabulatedbelow (Table 1) and shown in FIG. 1 .

TABLE 1 XRPD Peaks for Form B Angle (2θ ± 0.2°) Intensity (%) 18.2 100.09.6 86.7 9.1 80.7 18.7 55.8 12.7 24.1 8.5 23.9 10.0 15.6 20.1 14.8 21.713.9 23.2 12.3 12.4 12.2 16.1 9.6 14.3 9.2 6.2 8.9 15.6 7.7 27.4 6.926.4 6.6 29.7 6.2 27.1 6.0 25.0 5.0

Form B is characterized in providing at least one of the following 20values measured using CuKα radiation: 6.2, 14.3, and 15.6°.

Form B (from method 1) was analyzed by thermal techniques. DSC analysisindicated that Form B has a melting point with an onset at 275° C. and apeak at 276° C. TGA indicated that Form B exhibits a mass loss of about0.2% upon heating from about 25° C. to about 100° C. A representativeDSC/TGA thermogram of Form B is shown in FIG. 2 .

Example 62: Preparation of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideCrystalline Form D (Anhydrous Form)

5-6 mg of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(Example 20) was dissolved in mixed solvents of MeOH/DCM/H₂O (0.50ml/0.50 ml/0.20 ml), the clear solution was slowly evaporated in theambient condition to obtain a white solid. XRPD shows that the resultingwhite solid is6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideForm D.

Form D was analyzed by XRPD and the results are tabulated below (Table2) and shown in FIG. 3 .

TABLE 2 XRPD Peaks for Form D Angle (2θ ± 0.2°) Intensity (%) 9.6 100.018.4 43.0 13.1 32.0 19.9 17.9 27.1 17.3 9.2 15.9 21.7 14.0 23.4 11.224.5 9.6 19.3 8.8 16.8 8.7 22.2 8.3 16.3 8.0 18.8 7.6 25.4 6.9 10.2 6.633.0 6.3 22.5 5.8 12.6 5.7 7.9 4.5

Form D is characterized in providing at least one of the following 2θvalues measured using CuKα radiation: 7.9, 13.1 and 16.3°.

Single crystals of Form D were obtained from evaporation of the DMFsolution (or DMF/H₂O) of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide.Single crystal structure analysis confirmed that Form D is an anhydrousform. The molecular structure of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideForm D is shown in FIG. 4 . Crystallographic data: Space groupmonoclinic P2₁/c, unit cell dimensions: a=17.4559(8) Å, b=5.0647(2) Å,c=22.564(1) Å, β=92.609(1)°, V=1992.8(2) Å³.

Example 63: Preparation of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideMSA Crystalline Salt Form C (Anhydrous Form)

Method 1

427 mg of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(Example 20) was suspended in 8.0 ml of MeOH. To the suspension, 1.1 mlof 1.0 M aqueous MSA solution (1.1 mmol) was added, a clear solution wasobtained. The resulting solution was filtered, and the solvents of theclear solution was removed. The resulting solid was suspended in 1.0 mlof EtOH and 2.0 ml of THF, to obtain a slurry. The slurry was stirred atthe room temperature for 1 day. The solid was collected by filtrationand air-dried. 452 mg of off-white solid was obtained. XRD shows that6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamideMSA salt Form C was obtained.

Method 2

Methanesulfonic acid (16.8 g) was added to a stirring suspension of6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide(80.8 g, 92.8% w/w) in 4:1 v:v THF:ethanol (750 mL) at 25° C. Theresulting suspension was stirred at 25° C. for 16 h and then filtered.The solid was washed with 4:1 v:v THF:ethanol (300 mL) and then dried at35° C. under vacuum to give6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamidemesylate Form C (90.3 g) in 98% yield.

MSA-Form C from method 1 was analyzed by XRPD and the results aretabulated below (Table 3) and shown in FIG. 5 .

TABLE 3 XRPD Peaks for MSA-Form C Angle (2θ + 0.2°) Intensity (%) 17.5100.0 24.6 95.7 25.4 75.8 16.0 73.8 22.5 72.6 19.4 72.5 24.3 71.6 13.665.6 19.0 61.3 20.4 53.3 21.5 43.4 15.5 43.2 22.0 40.2 28.8 35.8 14.634.2 26.9 29.7 21.0 29.4 18.3 29.1 31.4 26.8 16.8 26.0

MSA-Form C obtained from method 1 was analyzed by thermal techniques.DSC analysis indicated that MSA-Form C starts to melting anddecomposition at the temperature with an onset at 254° C. and a peak at258° C. TGA indicated that MSA-Form C exhibits a mass loss of about 0.3%upon heating from about 25° C. to about 100° C. A representative DSC/TGAthermogram of MSA-Form C is shown in FIG. 6 .

Biological Assays

The following test procedures may be employed to determine theinhibitory properties of the compounds described herein.

PARP Fluorescence Anisotropy Binding Assays

Recombinant full length 6HIS tagged PARP1 protein was diluted to 6 nMwith 50 mM Tris pH 8, 0.001% Triton X100, 10 mM MgCl₂, 150 mM NaCl andincubated for four hours with an equivalent volume of 2 nM fluorescentprobe diluted with 50 mM Tris pH 8, 0.001% Triton X100, 10 mM MgCl₂, 150mM NaCl. The final DMSO concentration of the probe was kept below 1%(v/v).

Recombinant full length PARP2 protein was diluted to 6 nM with 50 mMTris pH 8, 0.001% Triton X100.10 mM MgCl₂, 150 mM NaCl and incubated forfour hours with an equivalent volume of 2 nM fluorescent probe dilutedwith 50 mM Tris pH 8, 0.001% Triton X100, 10 mM MgCl₂, 150 mM NaCl. Thefinal DMSO concentration of the probe was kept below 1% (v/v).

Recombinant full length PARP3 protein was diluted to 100 nM with 50 mMTris pH 8, 0.001% Triton X100, 10 mM MgCl₂, 150 mM NaCl and incubatedfor four hours with an equivalent volume of 6 nM fluorescent probediluted with 50 mM Tris pH 8, 0.001% Triton X100, 10 mM MgCl₂, 150 mMNaCl. The final DMSO concentration of the probe was kept below 1% (v/v).

Recombinant PARP5a binding domain was diluted to 160 nM with 50 mM TrispH 8, 0.001% Triton X100, 10 mM MgCl₂, 150 mM NaCl and incubated forfour hours with an equivalent volume of 6 nM fluorescent probe dilutedwith 50 mM Tris pH 8, 0.001% Triton X100, 10 mM MgCl₂, 150 mM NaCl. Thefinal DMSO concentration of the probe was kept below 1% (v/v).

Recombinant full length GST tagged PARP6 protein was diluted to 160 nMwith 50 mM Tris pH 8, 0.001% Triton X100, 10 mM MgCl₂, 150 mM NaCl andincubated for four hours with an equivalent volume of 6 nM fluorescentprobe diluted with 50 mM Tris pH 8, 0.001% Triton X100, 10 mM MgCl₂, 150mM NaCl. The final DMSO concentration of the probe was kept below 1%(v/v).

Fluorescence anisotropy of the probe when bound to the proteins wasmeasured using a BMG Pherastar FSX® in the presence of test compounds orsolvent control and the effect on anisotropy determined. % inhibitionvalues for different test compound concentrations were calculated andfitted to a four parameter logistic plot in order to determine the IC₅₀value. Where necessary, the compound K_(i) can be determined from theIC₅₀ value using a Munson Rodbard equation defined in Anal Biochem. 1980Sep. 1; 107(1):220-39 and is based on the known K_(D) of the probebinding to the relevant PARP protein

PARP Proliferation Assay (7 Day Compound Dosing)

DLD1 and BRCA2 (−/−) DLD1 cells were harvested to a density of 5000cells/ml and 2.5E4 cells/ml respectively in complete media, 40 μL/wellseeded into 384-well plates (Greiner, Kremsmunster, Austria; 781090)using a Multidrop Combi then incubated at 37° C., 5% CO₂ overnight. Nextday (Day 1) using a Multidrop Combi add sytoxgreen (5 ul, 2 uM) andsaponin (10 ul, 0.25% stock) to a day 0 plate, seal the plate using ablack adhesive lid and incubate for >3 h at rt. Cells were imaged usingCell Insight (Thermo Fisher) fitted with a 4× objective. Test compoundsare added using an Echo 555 and placed in incubator maintained at 37°C., 5% CO₂ and incubated for 7 days. On Day 8 add sytox green (5 ul, 2uM) and then saponin (10 ul, 0.25% stock) to plates, seal the plateusing a black adhesive lid and incubate for >3 h at rt. Read all cellson the Cell Insight with 4× Objective. The rate of proliferation isdetermined in Genedata by assessing the total cell number output fromthe Cell Insight for Day 0 and Day 8 plates.

In Vitro Human Transporter Efflux

MDCKII cells expressing MDR1 and BCRP were seeded onto polyethylenemembranes in 96-well Transwell insert systems at a density to form aconfluent cell monolayer. Test and reference compounds were diluted withthe transport buffer (HBSS HEPES pH7.4) to a concentration of 1 or 0.1μM. The final percent volume of the organic solvent was less than 1%.Permeation of the test compounds from A to B direction and from B to Adirection was determined over a 90-min incubation at 37° C. and 5% CO2with a relative humidity of 95%. At the end of the incubation, samplesfrom the apical and basolateral side were taken and then precipitatedwith cold acetonitrile containing internal standard. Aftercentrifugation at 4000 rpm, the supernatant was diluted with 0.1% formicacid aqueous solution and quantified by LC-MS/MS. The integrity of thecell monolayers was confirmed by using the marker Lucifer yellow.

The permeability coefficient (1×10-6 cm/s) was calculated using thefollowing equationPapp=(dCr/dt)×Vr/(A×C0)(1) The efflux ratio was calculated using the following equationEfflux ratio=Papp(B to A)/Papp(A to B)(2) where dCr/dt is the cumulative concentration of the compound in thereceiver chamber as a function of time (in μM/s); Vr is the solutionvolume in the receiver chamber (0.1 ml on the apical side and 0.3 ml onthe basolateral side); A is the surface area for the transport, that is,0.11 cm2 for the area of the monolayer; and C0 is the initialconcentration in the donor chamber (in μM).Determination of Fraction Unbound in Plasma

The fraction unbound was determined using the RED Device.

Compounds were prepared as 10 mM solutions in DMSO. A 1 mM working stockwas prepared by mixing up to 9 test compound (4 uL each) and 1 control(uL). If less than 9 test compounds were included then the additionvolume of blank DMSO was added to make up volume to 40 uL.

Frozen plasma was thawed in a water bath at 37° C. Plasma was thencentrifuged for 2 minutes at 4,000 rpm to remove clots and collectsupernatant into a fresh tube. The pH of the plasma was checked and onlyused if within the range of pH 7 to pH 8. 3 μL of the working solutionof each cassette was added to 597 μL of blank plasma and vortexed for 5minutes at 1000 rpm. The final percent volume of organic solvent is 0.5%and the final concentration for test compound was 5 μM. Immediatelytransfer 50 μL of the spiked plasma suspension to a 96-well plate to actas T=0 control sample. The samples are treated the same as the samplesafter incubation. The remaining plasma is kept at 37° C. prior tostarting the dialysis.

Place inserts open end up into the wells of the base plate. Add 300 μLof spiked plasma sample into the sample chamber, indicated by the redring. Add 500 μL of phosphate buffer (pH 7.4) to the buffer chamber.Cover the unit with gas permeable lid and incubate for 18 hours at 37°C. at 300 rpm with 5% CO2 on an orbital shaker in the CO2 incubator. Atthe end of incubation, remove lid and pipette 50 μL of post-dialysissamples from both buffer and plasma chambers into separated 96-wellplate for analysis, respectively.

Samples were matrix matched by adding 50 μL of blank rat plasma to thebuffer samples and an equal volume of PBS to the collected plasmasamples and vortexed to mix. 400 μL of acetonitrile containing anappropriate internal standard (IS) was added to precipitate protein andrelease compound and mixed by vortexing the plate for 10 minutesfollowed by centrifugation for 30 minutes at 4,000 rpm. 250 μL of thesupernatant was transferred to new 96-well plates and centrifuged again(4,000 rpm, 30 minutes). 100 μL of the supernatant was then transferredto new 96-well plates and mixed with 100 μL of distilled water to eachsample by vortex for 5 minutes at 1,000 rpm. Samples were analysed byLC-MS/MS and drug concentrations were determined vs a calibration curveproduced from spiked blank plasma with a typical range of 1-7500 nM.

The % unbound was determined as % Unbound=(Conc. buffer chamber/Conc.plasma chamber)×100%. Fraction unbound=% unbound/100.

Determination of Fraction Unbound in Brain Slice

The principle for the method for the determination of volume unbound inbrain slices has previously been published (Development of aHigh-Throughput Brain Slice Method for Studying Drug Distribution in theCentral Nervous System; Fridén et al, Drug Metabolism and Disposition,2009, 37 (6) 1226-1233). In brief:

Compound stock solutions were prepared in DMSO at the concentration of10 mM. A 1 mM working stock was prepared by mixing up to 9 test compound(4 uL each) and 1 control (4 uL). If less than 9 test compounds wereincluded, then blank DMSO was added to make up volume to 40 uL. On theday of the experiment 4 ul was diluted in 40 mL ECF buffer to give a 100nM solution of each test compounds which was then pre-warmed to 37° C.before the start of the incubation.

To prepare brain slices, rats weighing approximately 300 g wereterminally anesthetised with isoflurane by inhalation, the braincarefully removed and immersed in ice-cold oxygenated ECF buffer. Therat brain was transferred to a dish containing ice-cold, 02 supplied ECFbuffer and trimmed with razor before gluing to the tray of a microslicerwith the brain placed with the back section surface down centrally onthe tray. Ice cold ECF buffer was added to harden the glue and wet thebrain. The tray was placed in the microslicer and using a suitablecutting speed, 100-400 μm were cut slices until the striatum areaappeared. Four to six for each brain, 300 μm thick, coronal slices ofstriatum areas were cut and placed in ice cold 02 supplied buffer untilincubation. Six slices were transferred to the incubation traycontaining 40 mL pre warmed (37° C.) cassette mixture. The time fromwhen the brain is removed until the slices are in the cocktail mixturewas a maximum of 20 minutes. The incubation tray was covered with a gaspermeable lid and placed in a water bath with 02 pumped into it at 37°C. and incubated at a shaking frequency of 45 rpm for 5 h.

Before incubation, 200 μL of the non-incubated cassette solution issaved as the T=0 sample. 200 μL was then mixed with 200 μL blank brainhomogenate in ECF buffer (4 volumes (w/v). After incubation the pH inthe cassette solution is measured and recorded, and the pH value must beabove 7.3. 200 μL from the surface of the cassette solution wastransferred in to a tube containing 200 μL blank brain homogenate in ECFbuffer (4 volumes (w/v)). Each brain slice is dried on a filter paperand weighed in a 2 mL eppendorf tube. After addition of 9 volumes (w/v)of ECF buffer the slices are homogenized with a sonicator. The sampleswere precipitated and diluted as below. 50 μL aliquots from each sampleand 3×50 μL from each cassette solution (mixed with blank homogenate)were transferred to 0.6 mL centrifuge tubes. The samples areprecipitated with 200 μL ice cold acetonitrile containing internalstandard and vortexed at 2,000 rpm for 3 minutes followed bycentrifugation at 14000 rpm, for 15 minutes at 4° C. 100 μL of thesupernatant was transferred to a new 96-well plate for analysis and 100μL of distilled water to each sample and the plate shaken for 2 minutesat 1000 rpm for analysis by LC-MS/MS.

Then the mixed slice samples are further diluted in two steps, 10 and100 times with double blank samples prepared with 150 μL of blank brainhomogenate in ECF buffer (4 volumes (w/v)) are transferred to 1.5 mLcentrifuge tubes containing 150 μL of ECF buffer, vortexed at 2,000 rpmfor 2 minutes. The samples are precipitated with 1200 μL ice coldacetonitrile and vortexed at 2,000 rpm for 3 minutes followed bycentrifugation at 14000 rpm, for 15 minutes at 4° C. Then transfer 100μL of the supernatant to a new 96-well plate for analysis. Add 100 μL ofdistilled water to each sample to obtain the double blank samples.

The unbound volume brain (V_(u,brain)) was calculated asV_(u)=(C_(slice)V₀*C_(ECF))/(1−V₀)*C_(ECF)

Where C_(slice), C_(ECF) and V₀ are amount of drug in the slice, thedrug concentration in the ECF (representing the drug concentration inthe brain ECF, i.e. the free concentration), and the water adhesion ofthe brain slice (0.0931), respectively.

The fraction unbound in brain f_(u,brain)=1/V_(u,brain)

Determination of Kpuu in Rat

The ratio of total/unbound drug in plasma to total/unbound drug in brain(Kp/Kpuu) was determined as follows.

Compounds were formulated as a mixture at a concentration of 0.5 mM eachin 1:1:1 tetraethyleneglycol:dimethylacetamide:water and administered toHan Wistar rats via intravenous infusion at 2 □mols/kg/h in a volume of4 mL/kg. After 4 h the animals were sacrificed, and brain and bloodsamples collected. Plasma was prepared from blood and all samples werestored frozen at −20° C. until analysis. Following collection brainsamples were homogenised in purified water at a ratio of 1:3 (w/v) andstored frozen at −20° C. until analysis.

Plasma and brain samples were analysed by protein precipitation followedby LC-MS/MS and concentrations determined against a calibration curvegenerated by spiking blank rat plasma or brain homogenate with drugacross an appropriate concentration range. The brain concentration wascorrected for the residual blood by subtracting 0.8% of the plasmaconcentration from the total brain concentration.

The Kp was then calculated as: Kp=((4*[brainhomogenate])−(0.008*[plasma]))/[plasma]

The Kpuu was then calculated as: Kpuu=Kp*(fraction unbound in brainslice/fraction unbound in plasma)

Biological Data

TABLE 4 BRCA2 −/− WT MDCK- DLD-1 DLD-1 MDR1- PARP1 PARP2 PARP3 PARP5aPARP6 hERG prolif. prolif. BCRP Example IC50 IC50 IC50 IC50 IC50 IC50 7d IC50 7 d IC50 Efflux Rat Number (μM) (μM) (μM) (μM) (μM) (μM) (μM)(μM) Ratio Kpuu 1 0.004 >70 >100 >100 >100 >40 0.014 24 0.7 0.07 2 0.01115 >40 0.734 3 0.003 >100 >100 >100 >100 >40 0.008 25 1.3 4 0.005 >8378 >100 >100 >40 0.081 >14 0.8 0.13 5 0.005 >63 2.89 6 0.004 >100 70.006 58 8.43 >30 8 0.004 >66 >100 >100 >100 >40 0.012 >7.9 90.004 >100 >100 >100 >100 >40 0.01 >10 0.4 100.013 >100 >100 >100 >100 >40 >30.0 >30 11 0.003 >100 >100 >100 >100 >400.009 >30 12 0.015 85 >100 >100 >40 0.008 4.2 13 0.009 >10062 >100 >100 >40 0.019 22 3.0 14 0.013 >83 52 >100 >100 >40 0.015 3.7 150.012 >100 43 >100 >100 >38 0.014 3.7 16 0.01 >100 >100 >29 >100 >403.62 >30 17 0.006 >100 >100 >100 >100 >40 1.05 >10 180.005 >100 >100 >100 >100 14 4.33 21 19 0.013 40 >40 0.006 2.4 20<0.005 >93 >100 >100 >100 >40 0.008 >30 1.1 0.27 21 0.007 >1005.8 >100 >100 >40 1.42 1.6 22 0.006 87 23 0.005 >67 >100 >100 >100 >400.003 >30 0.8 0.62 24 0.006 >81 >100 >100 >100 >36 0.003 >30 1.1 250.005 >100 0.297 26 0.005 88 27 0.004 >64 >100 >100 >100 >40 0.006 6.30.8 0.43 28 0.005 >100 >100 >100 >100 >38 0.004 0.8 290.015 >100 >100 >100 >100 >40 0.005 >10 0.7 0.33 300.006 >100 >100 >100 >100 >40 0.003 >30 1.8 310.007 >100 >100 >100 >100 >40 0.007 >30 1.6 0.19 320.007 >100 >100 >100 >100 >40 1.08 23 33 0.167 >100 >30.0 34 0.026 >10029 8.44 35 0.03 >100 10.3 >30 36 0.022 >100 16.2 37 0.026 57 0.01 5.0 380.012 21 >100 >100 >100 >40 0.547 39 0.006 >100 >100 >100 >100 >40 0.0081.9 40 0.011 >100 >100 13 >100 >40 0.007 2.0 410.005 >100 >100 >100 >100 >40 0.007 2.4 42 0.005 >88 0.006 43 0.005 >1000.01 44 0.128 >100 >30.0 45 0.006 >100 0.006 1.5 46 0.01 >100 0.013 470.076 >100 >100 >100 >100 >40 0.058 48 0.039 26 >100 >100 >100 >40 0.01827 8.8 49 0.043 11 >29 >100 >100 >40 0.041 50 0.060 35 >40 0.136 510.006 1.2 52 0.085 3.8 53 0.026 >100 54 0.111 >100 55 0.005 >100 560.008 >100 57 0.011 >100 58 0.008 >100 59 0.006 2.1 60 0.023 >100

The invention claimed is:
 1. A compound which is:6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide:

or a pharmaceutically acceptable salt thereof.
 2. The compound accordingto claim 1 which is:6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide.3. A pharmaceutical composition comprising a compound or apharmaceutically acceptable salt thereof according to claim 1, and atleast one pharmaceutically acceptable diluent, excipient or inertcarrier.
 4. The pharmaceutical composition of claim 3 comprising6-fluoro-5-[4-[(5-fluoro-2-methyl-3-oxo-4H-quinoxalin-6-yl)methyl]piperazin-1-yl]-N-methyl-pyridine-2-carboxamide.